Commands such as `./dev test --verbose` might previously would produce
two log lines everytime it happens to have to call the genrule for
execgen targets:

```
INFO: From Executing genrule //pkg/sql/colexec/colexecwindow:gen-window-framer:
initialized metamorphic constant "span-reuse-rate" with value 10
```

This is because execgen has the tracing package in its dependency tree

```
> go list -f '{{ join .Deps "\n" }}' ./pkg/sql/colexec/execgen/ | grep tracing | head -1
github.com/cockroachdb/cockroach/pkg/util/tracing
```

and that package instantiates this metamorphic constant.

This PR sets COCKROACH_INTERNAL_DISABLE_METAMORPHIC_TESTING=true when
calling the generator so we don't get metamorphic constants enabled.

Something like cockroachdb#75065 would give us more complete coverage of commands
that might be generating noise.

Release note: None

76210: util/tracing: reduce allocations in EnsureForkSpan r=andreimatei a=andreimatei

This patch pre-allocates capacity for the options slice in
EnsureForkSpan. Before, we were reallocating the slice storage
repeatedly, as it was growing from 0 to 1 and from 1 to 2 elements.

This patch also simplifies, and slighly speeds up, EnsureChildSpan. This
guy was using a sync.Pool for its options slice. That is not necessary,
since the slice storage does not escape.

In the benchmarks below, detached-child=false is EnsureChildSpan and
detached-child=true is EnsureForkSpan.

> make bench PKG=./pkg/util/tracing BENCHES=BenchmarkSpanCreation TESTFLAGS="-count=5 -cpu=1,2,4,8,16"
name                                  old time/op    new time/op    delta
SpanCreation/detached-child=false       1.70µs ± 1%    1.61µs ± 1%   -5.06%  (p=0.008 n=5+5)
SpanCreation/detached-child=false-2     1.17µs ± 7%    1.04µs ± 3%  -10.70%  (p=0.008 n=5+5)
SpanCreation/detached-child=false-4      958ns ± 2%     893ns ±10%   -6.76%  (p=0.008 n=5+5)
SpanCreation/detached-child=false-8     1.11µs ±38%    0.95µs ± 1%     ~     (p=0.310 n=5+5)
SpanCreation/detached-child=false-16     925ns ± 1%     919ns ± 1%     ~     (p=0.286 n=4+5)
SpanCreation/detached-child=true        2.27µs ± 2%    1.88µs ± 0%  -17.27%  (p=0.008 n=5+5)
SpanCreation/detached-child=true-2      1.82µs ±10%    1.33µs ±22%  -26.81%  (p=0.008 n=5+5)
SpanCreation/detached-child=true-4      1.29µs ± 2%    1.02µs ± 1%  -21.35%  (p=0.008 n=5+5)
SpanCreation/detached-child=true-8      1.16µs ± 1%    0.91µs ± 5%  -21.56%  (p=0.008 n=5+5)
SpanCreation/detached-child=true-16     1.14µs ± 2%    0.97µs ± 1%  -15.08%  (p=0.008 n=5+5)

name                                  old alloc/op   new alloc/op   delta
SpanCreation/detached-child=false         288B ± 0%      288B ± 0%     ~     (all equal)
SpanCreation/detached-child=false-2       288B ± 0%      288B ± 0%     ~     (all equal)
SpanCreation/detached-child=false-4       288B ± 0%      288B ± 0%     ~     (all equal)
SpanCreation/detached-child=false-8       288B ± 0%      288B ± 0%     ~     (all equal)
SpanCreation/detached-child=false-16      288B ± 0%      288B ± 0%     ~     (all equal)
SpanCreation/detached-child=true          768B ± 0%      288B ± 0%  -62.50%  (p=0.008 n=5+5)
SpanCreation/detached-child=true-2        768B ± 0%      288B ± 0%  -62.50%  (p=0.008 n=5+5)
SpanCreation/detached-child=true-4        768B ± 0%      288B ± 0%  -62.50%  (p=0.008 n=5+5)
SpanCreation/detached-child=true-8        768B ± 0%      288B ± 0%  -62.50%  (p=0.008 n=5+5)
SpanCreation/detached-child=true-16       769B ± 0%      288B ± 0%  -62.55%  (p=0.008 n=5+5)

name                                  old allocs/op  new allocs/op  delta
SpanCreation/detached-child=false         6.00 ± 0%      6.00 ± 0%     ~     (all equal)
SpanCreation/detached-child=false-2       6.00 ± 0%      6.00 ± 0%     ~     (all equal)
SpanCreation/detached-child=false-4       6.00 ± 0%      6.00 ± 0%     ~     (all equal)
SpanCreation/detached-child=false-8       6.00 ± 0%      6.00 ± 0%     ~     (all equal)
SpanCreation/detached-child=false-16      6.00 ± 0%      6.00 ± 0%     ~     (all equal)
SpanCreation/detached-child=true          16.0 ± 0%       6.0 ± 0%  -62.50%  (p=0.008 n=5+5)
SpanCreation/detached-child=true-2        16.0 ± 0%       6.0 ± 0%  -62.50%  (p=0.008 n=5+5)
SpanCreation/detached-child=true-4        16.0 ± 0%       6.0 ± 0%  -62.50%  (p=0.008 n=5+5)
SpanCreation/detached-child=true-8        16.0 ± 0%       6.0 ± 0%  -62.50%  (p=0.008 n=5+5)
SpanCreation/detached-child=true-16       16.0 ± 0%       6.0 ± 0%  -62.50%  (p=0.008 n=5+5)

Release note: None

76308: changefeedccl: remove methods from testServerShim r=miretskiy a=stevendanna

In #75852 these methods have recently been added to the underlying
TestTenantInterface, so we no longer need to stub them out in this
shim.

Release note: None

76309: build: disable metamorphic constants when calling execgen r=irfansharif a=stevendanna

Commands such as `./dev test --verbose` might previously produce
two log lines everytime it happens to have to call the genrule for
execgen targets:

```
INFO: From Executing genrule //pkg/sql/colexec/colexecwindow:gen-window-framer:
initialized metamorphic constant "span-reuse-rate" with value 10
```

This is because execgen has the tracing package in its dependency tree

```
> go list -f '{{ join .Deps "\n" }}' ./pkg/sql/colexec/execgen/ | grep tracing | head -1
github.com/cockroachdb/cockroach/pkg/util/tracing
```

and that package instantiates this metamorphic constant.

This PR sets COCKROACH_INTERNAL_DISABLE_METAMORPHIC_TESTING=true when
calling the generator so we don't get metamorphic constants enabled.

Something like #75065 would give us more complete coverage of commands
that might be generating noise.

Release note: None

76338: jobs: De-flake TestTransientTxnErrors test. r=miretskiy a=miretskiy

Fix rare, but silly flake in TestTransientTxnErrors where the
`executeSchedules` go routine could run before we were ready.

Fixes #65045

Release Notes: None

Co-authored-by: Andrei Matei <andrei@cockroachlabs.com>
Co-authored-by: Steven Danna <danna@cockroachlabs.com>
Co-authored-by: Yevgeniy Miretskiy <yevgeniy@cockroachlabs.com>

Commands such as `./dev test --verbose` might previously would produce
two log lines everytime it happens to have to call the genrule for
execgen targets:

```
INFO: From Executing genrule //pkg/sql/colexec/colexecwindow:gen-window-framer:
initialized metamorphic constant "span-reuse-rate" with value 10
```

This is because execgen has the tracing package in its dependency tree

```
> go list -f '{{ join .Deps "\n" }}' ./pkg/sql/colexec/execgen/ | grep tracing | head -1
github.com/cockroachdb/cockroach/pkg/util/tracing
```

and that package instantiates this metamorphic constant.

This PR sets COCKROACH_INTERNAL_DISABLE_METAMORPHIC_TESTING=true when
calling the generator so we don't get metamorphic constants enabled.

Something like cockroachdb#75065 would give us more complete coverage of commands
that might be generating noise.

Release note: None