fix: updates automl dependency and missing pandas install

[chalmerlowe]

Resolves several issues that cause CI/CD to fail.

CHANGES:

• Update post-processing to bump google-auth to >=2.26.1 to prevent dependency resolution issue.
• Update post-processing to ensure pandas is installed as an extra.
• Move post-processing yaml elements to a standalone automl-integration.yaml file.

Fixes #17131 🦕

[gemini-code-assist]

Code Review

This pull request enables generation for the automl library and introduces a post-processing configuration to update google-auth dependencies, add extra requirements, and export new clients. Feedback suggests improving the robustness of the post-processing regex patterns by using flexible version matching instead of hardcoded strings and correcting syntax errors in the search patterns, such as unescaped brackets and unnecessary backslashes in indentation.

[gemini-code-assist]

The search pattern for dependencies has two issues that should be addressed:

1. Hardcoded Versions: It hardcodes specific version strings for multiple dependencies (e.g., grpcio, proto-plus). According to the general rules, you should use flexible regex patterns (like .* or [\s\S]*) to match version strings. This ensures the replacement continues to work even if the generated versions change in the future.
2. Regex Error: On line 22, the opening bracket in [grpc\] is not escaped. It should be \[grpc\] to correctly match the literal string [grpc]. Without the escape, it will be treated as a regex character class, which will cause the match to fail.

Consider using a more flexible pattern for the versions to improve robustness.

    before: |
      dependencies = \[
          "google-api-core\[grpc\] .*",
          # Exclude incompatible versions of `google-auth`
          # See https://github.com/googleapis/google-cloud-python/issues/12364
          "google-auth .*",
          "grpcio .*",
          "grpcio .*",
          "proto-plus .*",
          "proto-plus .*",
          "protobuf .*",

References

1. When defining search patterns for automated code replacements in librarian post-processing YAML files, use flexible regex patterns (such as [\s\S]*) to match version strings instead of hardcoding specific versions. This ensures the replacement logic remains functional even when dependency versions are updated in the source files, preventing match failures.

[gemini-code-assist]

There is an unnecessary backslash before the indentation spaces. This will likely cause the regex to fail to match the intended line in noxfile.py. Indentation in YAML block scalars is preserved, so you should just use spaces to match the indentation of the target code.

          \)