[BAZEL] Fix CI after bazel 9.0.0 release

[marcalff]

Fixes # (issue)

Context

Per https://github.com/google/oss-policies-info/blob/main/foundational-cxx-support-matrix.md,
only Bazel 8 LTS is supported, so we should no longer use bazel 7.

Per https://github.com/bazelbuild/bazel/releases/tag/9.0.0,
bazel 9.0.0 is now released.

This exposed a bug in github runners: actions/runner-images#13564

The build with bazel 9.0.0 is broken for multiple reasons, including:

• [9.0.0rc2] Confusing issue when load statement is missing for a provider bazelbuild/bazel#27684
• MODULE.bazel: bazel_compatibility constraint breaks when a module dep has invalid syntax for current bazel bazelbuild/bazel#28350
• changes related to rules_cc in bazel 9 for C++
• changes related to protobuf / protoc being embedded in bazel 9

which altogether prevents to build older grpc packages with C++14 and bazel 9.

Changes

Please provide a brief description of the changes here.

• Change .bazelversion to 8.5.0 for local builds
• Add a work around in CI to pick the correct bazel version in github runners

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.96%. Comparing base (e9035a3) to head (a22022e).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3823   +/-   ##
=======================================
  Coverage   89.96%   89.96%           
=======================================
  Files         225      225           
  Lines        7167     7167           
=======================================
  Hits         6447     6447           
  Misses        720      720           

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