Close out migration for absl_grpc_proto

[regro-cf-autotick-bot]

This PR has been triggered in an effort to close out the migration for absl_grpc_proto.

Notes and instructions for merging this PR:

1. Please merge the PR only after the tests have passed.
2. Feel free to push to the bot's branch to update this PR if needed.

Please note that if you close this PR we presume that the feedstock has been rebuilt, so if you are going to perform the rebuild yourself don't close this PR until the your rebuild has been merged.

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_{This PR was created by the regro-cf-autotick-bot. The regro-cf-autotick-bot is a service to automatically track the dependency graph, migrate packages, and propose package version updates for conda-forge. Feel free to drop us a line if there are any issues! This PR was generated by https://github.com/regro/cf-scripts/actions/runs/14561646077 - please use this URL for debugging.}

[conda-forge-admin]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe/meta.yaml) and found it was in an excellent condition.

[h-vetinari]

Ah, it's been a while since we got through all the feedstocks with any children in a protobuf migration (xref #4075) - I was planning to close this one soon, but well, might as well take it. Here are the remaining feedstocks that didn't make it:

Worked on

• Rebuild for libabseil 20250127, libgrpc 1.71 & libprotobuf 5.29.3 google-cloud-cpp-feedstock#196 (see here)
• Rebuild for libabseil 20250127, libgrpc 1.71 & libprotobuf 5.29.3 ray-packages-feedstock#204
• Rebuild for libabseil 20250127, libgrpc 1.71 & libprotobuf 5.29.3 tensorflow-feedstock#424

Needs a motivated maintainer/contributor

• Rebuild for libabseil 20250127, libgrpc 1.71 & libprotobuf 5.29.3 mongodb-feedstock#101
• Rebuild for libabseil 20250127, libgrpc 1.71 & libprotobuf 5.29.3 or-tools-feedstock#65
• Rebuild for libabseil 20250127, libgrpc 1.71 & libprotobuf 5.29.3 pyg-lib-feedstock#35
• Rebuild for libabseil 20250127, libgrpc 1.71 & libprotobuf 5.29.3 xilinx-runtime-feedstock#40

Dead feedstocks

• Rebuild for libabseil 20250127, libgrpc 1.71 & libprotobuf 5.29.3 bear-feedstock#54
• Rebuild for libabseil 20250127, libgrpc 1.71 & libprotobuf 5.29.3 go-cockroach-feedstock#32
• Rebuild for libabseil 20250127, libgrpc 1.71 & libprotobuf 5.29.3 tomviz-feedstock#73

[h-vetinari]

Ah, we did break stuff here though. And like for #5559, we're in the situation where we need to keep the migration open to not bump the macos baseline, see conda-forge/conda-forge.github.io#2467

[h-vetinari]

Fixed in 3a22222