Removes several ports from the registry that conflict with others and/or are effectively untested in vcpkg's build lab.

[cppmicroservices] This port was added 5 years ago, appears relatively unused, only exists in repology due to vcpkg, and is full of vendored dependencies. It's also broken for most official triplets. Replaces microsoft#34552
[ijg-libjpeg, mozjpeg] Leaf ports that we can't test and conflict with libjpeg-turbo, the curated registry's canonical jpeg implementation.
[optional-bare] Conflicted with optional-lite.
[qt5-canvas3d] Removed by qt5 upstream.
[range-v3-vs2015] No longer maintained by upstream, no longer necessary in 2024.
[rbdl-orb] File conflicts with its own dependency.
[sciter] Left support by upstream 2 years ago and has conflicts with other ports.
[signalrclient] "Obsolete" and conflicts with microsoft-signalr
[spdk-*] Several conflicts with other ports.
[c-dbg-macro] Conflicts with [dbg-macro]
[casadi] microsoft#41649 appears to have been merged in error, casadi/casadi#3896 needs to land before this can be in the curated registry. Moreover, problems in the portfile were skipped in ci.baseline.txt rather than a supports expression. We are happy to bring this port back as soon as that issue is fixed :)
[chromium-base] Not tested anywhere for years.
[libmesh] Conflicts with other ports.
[libpng-apng] Doesn't even exist in the first place.
[libqcow] Release distribution file contains configured sources, while the source code in the repository does not.
[libvmdk] Upstream is gone.
[mecab] Upstream has not been edited in 10 years, combination of =skip and supports clause means not tested.
[shogun] Not tested.

Not deindexed:
[bde] Conflicts with other ports. Warning was given more than a year ago: microsoft#32645 .
However, microsoft#41335 appears to indicate that it works now, so the =skips were removed.
[stxxl] Appears to work on my machine?
[chartdir] Unstable download URLs are now mitigated by asset caching.
[buck-yeh-bux] Looks like these are intended to be in the supports clause.
[boringssl, fluidlite, libressl, libmariadb, libmysql] Appears to have a dedicated userbase despite being untestable in CI.
[libxaw] Needed supports expression for ONLY_DYNAMIC_LIBRARY, should have always been a fail not a skip.

Related: microsoft#42165