test(spanner): clear context-aware mTLS env var in unit tests

[sakthivelmanii]

Unset CLOUDSDK_CONTEXT_AWARE_USE_CLIENT_CERTIFICATE in mTLS unit tests to prevent failures in Google and Kokoro CI environments.

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Fixes #<issue_number_goes_here> 🦕

[gemini-code-assist]

Code Review

This pull request updates the GAPIC generator templates and Google Cloud Spanner unit tests to properly handle the CLOUDSDK_CONTEXT_AWARE_USE_CLIENT_CERTIFICATE environment variable by popping it during mTLS endpoint tests. It also sets GOOGLE_API_USE_CLIENT_CERTIFICATE to "false" when testing specific GOOGLE_API_USE_MTLS_ENDPOINT behaviors. The reviewer recommends also explicitly setting CLOUDSDK_CONTEXT_AWARE_USE_CLIENT_CERTIFICATE to "false" in those same test cases to avoid test failures in environments where it is set to "true".

[gemini-code-assist]

To prevent test failures in environments where CLOUDSDK_CONTEXT_AWARE_USE_CLIENT_CERTIFICATE is set to "true", we should also explicitly set it to "false" in this mock.patch.dict call, similar to how GOOGLE_API_USE_CLIENT_CERTIFICATE is handled.

 with mock.patch.dict(os.environ, {"GOOGLE_API_USE_MTLS_ENDPOINT": "never", "GOOGLE_API_USE_CLIENT_CERTIFICATE": "false", "CLOUDSDK_CONTEXT_AWARE_USE_CLIENT_CERTIFICATE": "false"}):

[gemini-code-assist]

To prevent test failures in environments where CLOUDSDK_CONTEXT_AWARE_USE_CLIENT_CERTIFICATE is set to "true", we should also explicitly set it to "false" in this mock.patch.dict call, similar to how GOOGLE_API_USE_CLIENT_CERTIFICATE is handled.

 with mock.patch.dict(os.environ, {"GOOGLE_API_USE_MTLS_ENDPOINT": "always", "GOOGLE_API_USE_CLIENT_CERTIFICATE": "false", "CLOUDSDK_CONTEXT_AWARE_USE_CLIENT_CERTIFICATE": "false"}):

[parthea]

Wait for #17880 to be merged first

[parthea]

@sakthivelmanii , Please could you resolve the conflicts?

[parthea]

These are auto-generated files. I'll take a look

[parthea]

Please review failing tests if this change is still needed. I'm going to switch this to draft since presubmits are failing

Fixed