Picks up two PRs that improved the performance of Quo, Sqrt, Cbrt, Exp, Ln, Log, and Pow:

• apd: optimize Quo, remove per-digit long division  apd#114
• apd: don't strip trailing zeros in Quo and Sqrt apd#115

Almost all of the testing changes here are due to the rounding behavior in cockroachdb/apd#115. This brings us closer to PG's behavior, but also creates a lot of noise in this diff. To verify that this noise wasn't hiding any correctness regressions caused by the rewrite of Context.Quo in the first PR, I created #75757, which only includes the first PR. #75757 passes CI with minimal testing changes. The testing changes that PR did require all have to do with trailing zeros, and most of them are replaced in this PR.

Release note (performance improvement): The performance of many DECIMAL arithmetic operators has been improved by as much as 60%. These operators include division (/), sqrt, cbrt, exp, ln, log, and pow.

Speedup on TPC-DS dataset

The TPC-DS dataset is full of decimal columns, so it's a good playground to test this change. Unfortunately, the variance in the runtime performance of the TPC-DS queries themselves is high (many queries varied by 30-40% per attempt), so it was hard to get signal out of them. Instead, I imported the TPC-DS dataset with a scale factor of 10 and ran some custom aggregation queries against the largest table (web_sales, row count = 7,197,566):

# q1
select sum(ws_wholesale_cost / ws_ext_list_price) from web_sales;

# q2
select sum(ws_wholesale_cost / ws_ext_list_price - sqrt(ws_net_paid_inc_tax)) from web_sales;

Here's the difference in runtime of these two queries before and after this change on an n2-standard-8 instance:

name              old s/op   new s/op   delta
TPC-DS/custom/q1  22.4 ± 0%   8.6 ± 0%  -61.33%  (p=0.002 n=6+6)
TPC-DS/custom/q2  91.4 ± 0%  32.1 ± 0%  -64.85%  (p=0.008 n=5+5)