Remove entry point helper scripts

[ViktorHofer]

NO MERGE, part of batched rollout cycle: #33821

The entry point helper scripts were useful during the consolidation of the repositories. This work is mostly done and the build.cmd/sh script should be used going forward to promote a single entrypoint to build the repository and being able to build multiple subsetcategories at once.

TODO before merging:

• Create/update an announcement issue
• Announce in gitter channel

cc @stephentoub @jkotas @danmosemsft @steveisok @dotnet/runtime-infrastructure

[jkotas]

LGTM, once it passes the CI.

[danmoseley]

This is the right direction, but I thought we were rolling changes that break developer workflow into batches to avoid contributor fatigue.

Would it cause expense to just hold this for 2 or 3 weeks into a batch of workflow breaks in say mid April (I made that up)?

[ViktorHofer]

sure, I applied the no merge label anyway.

[ViktorHofer]

This will break source-indexer, therefore I'm updating it pro-actively: https://github.com/dotnet/source-indexer/blob/5210eb17a3b615c1c4aa57425f35271eaa340066/src/index/repositories.props#L4-L33.

[safern]

Other than my 2 comments, LGTM.

[ViktorHofer]

Would it cause expense to just hold this for 2 or 3 weeks into a batch of workflow breaks in say mid April (I made that up)?

@danmosemsft Created #33821 to track the rollout of this change.

[ViktorHofer]

Rebased and queued official build: https://dnceng.visualstudio.com/internal/_build/results?buildId=590038