chore: remove grpc-dynamic-codegen example

[pichlermarc]

Which problem is this PR solving?

Removes the grpc-dynamic-codegen example for the following reasons:

• the example is using outdated package versions
• the example uses the grpc package which is not supported by the latest version of @opentelemetry/instrumentation-grpc(see chore(instrumentation-grpc): drop support for grpc opentelemetry-js#3807)
• @opentelemetry/instrumentation-grpc is not part of this repo anymore.

[codecov]

Codecov Report

Merging #1871 (d4f6bad) into main (44cba00) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1871   +/-   ##
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  Coverage   91.45%   91.45%           
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  Files         144      144           
  Lines        7406     7406           
  Branches     1483     1483           
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  Hits         6773     6773           
  Misses        633      633