[CI] Benchmark workflow fails, C++14 required to build grpc

[marcalff]

Fixes #2083

Changes

There are two benchmarks workflows defined in CI:

• per PR push benchmark (ci.yml)
• benchmark on the main branch (benchmark.yml)

The former uses local tests, while the later uses an opentelemetry collector in docker.

Currently, ci.yml builds properly, while benchmark.yml fails to build.

Fixed the build for benchmark.yml:

• aligned the workflow definition on ci.yml
• in do_ci.sh, aligned compiler flags for bazel.benchmark on flags used in benchmark

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

Merging #2278 (a4e5724) into main (628838a) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2278   +/-   ##
=======================================
  Coverage   87.52%   87.52%           
=======================================
  Files         199      199           
  Lines        5981     5981           
=======================================
  Hits         5234     5234           
  Misses        747      747           

[lalitb]

Thanks for fixing this.