fix: disambiguate google-cloud-bigquery to_dataframe usage from pandas-gbq in ua.

[tswast]

For internal issue b/540939659 and a follow-up to #18364

🦕

[gemini-code-assist]

Code Review

This pull request updates the BigQuery client to include the google-cloud-bigquery version as a legacy identifier in the user agent string for to_dataframe and to_arrow operations, and adds corresponding unit tests. The review feedback suggests aliasing the imported version module to bq_version to avoid potential shadowing conflicts, and removing redundant local imports of the sys module within several test functions in test_table.py.

[gemini-code-assist]

Importing the version module as version can easily lead to shadowing issues or confusion because version is a very common variable and parameter name throughout this codebase. Consider aliasing it to bq_version to prevent potential naming conflicts.

Suggested change

	version,
	version as bq_version,

[gemini-code-assist]

Use the aliased bq_version to avoid potential shadowing issues with the common name version.

Suggested change

	user_agent = f"legacy-gcb/{version.__version__} {pandas_user_agent}"
	user_agent = f"legacy-gcb/{bq_version.__version__} {pandas_user_agent}"

[gemini-code-assist]

According to the general rules, do not import modules inside functions if they are already imported at the module level. Since sys is already imported at the module level of this file, this local import is redundant and can be removed.

Suggested change

	import sys
	import google.auth.credentials
	import google.auth.credentials

References

1. Do not import modules or classes inside functions if they are already imported at the module level.

[gemini-code-assist]

According to the general rules, do not import modules inside functions if they are already imported at the module level. Since sys is already imported at the module level of this file, this local import is redundant and can be removed.

Suggested change

	import sys
	import google.auth.credentials
	import google.auth.credentials

References

1. Do not import modules or classes inside functions if they are already imported at the module level.

[gemini-code-assist]

According to the general rules, do not import modules inside functions if they are already imported at the module level. Since sys is already imported at the module level of this file, this local import is redundant and can be removed.

Suggested change

	import sys
	import google.auth.credentials
	import google.auth.credentials

References

1. Do not import modules or classes inside functions if they are already imported at the module level.

[gemini-code-assist]

According to the general rules, do not import modules inside functions if they are already imported at the module level. Since sys is already imported at the module level of this file, this local import is redundant and can be removed.

Suggested change

	import sys
	import google.auth.credentials
	import google.auth.credentials

References

1. Do not import modules or classes inside functions if they are already imported at the module level.