fix(sqlalchemy-bigquery): wrap string in WKT in geography system tests

[ohmayr]

Wraps spatial string parameters with WKT(...) in ST_Contains and ST_Intersects system test queries. This ensures GeoAlchemy2 compiles ST_GeogFromText(...) so BigQuery receives GEOGRAPHY parameters instead of throwing argument type mismatch errors (GEOGRAPHY, STRING). Unskips geography system tests.

Towards #17287 🦕

[gemini-code-assist]

Code Review

This pull request unskips several GeoAlchemy2 system tests (test_geoalchemy2_core, test_geoalchemy2_orm, and test_geoalchemy2_orm_w_relationship) in packages/sqlalchemy-bigquery/tests/system/test_geography.py. To resolve the previous failures, the spatial string literals in the queries are now wrapped with WKT imported from sqlalchemy_bigquery. There are no review comments, and I have no additional feedback to provide.

[parthea]

LGTM but holding off on formal approval. Please also update the unit test here

google-cloud-python/packages/sqlalchemy-bigquery/tests/unit/test_geography.py

Lines 27 to 29 in 81390d5

	# TODO(http://github.com/googleapis/google-cloud-python/issues/17287): Unskip once bug is resolved.
	@pytest.mark.skip(reason="Failing in CI with AssertionError.")
	deftest_geoalchemy2_core(faux_conn, last_query):

[parthea]

Approving the system test fix. The unit test fix review is in a separate PR : #17769