fix: let BigQuery infer dataset location for view creation

[caohy1988]

Summary

Fixes #5476

The plugin passed location=self.location (default "US") to bigquery.Client(). This only affects query job routing — not table CRUD or the Storage Write API. When a dataset lives in a non-US region, view creation DDL queries silently fail with a location mismatch.

Fix

Remove location=self.location from the bigquery.Client() constructor. When the client has no default location and client.query(sql) is called without an explicit location parameter, the BQ API infers the job location from the dataset referenced in the DDL statement.

Traced through the BQ Python client:

1. client.query(sql) — location param defaults to None, falls back to self.location which is also None
2. _to_query_request() — when location is None, the "location" key is not included in the API request
3. BQ API — infers location from the dataset referenced in CREATE OR REPLACE VIEW

One line of production code changed. Everything else is test updates.

What changes

Operation	Before	After
Table CRUD	Works	Same
Storage Write API	Works	Same
View creation (non-US dataset)	Silent failure	Works — BQ infers location

Test plan

• 211 tests pass, 0 regressions
• test_client_created_without_location — verifies bigquery.Client() is called without location kwarg
• test_view_query_omits_location — verifies client.query() is called without explicit location
• test_view_error_still_logged — view creation errors don't crash initialization

🤖 Generated with Claude Code

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[adk-bot]

Response from ADK Triaging Agent

Hello @caohy1988, thank you for creating this PR!

Before we can review your contribution, you'll need to sign the Contributor License Agreement (CLA). You can do so at https://cla.developers.google.com/.

Once the CLA is signed, we will be able to proceed with the review. Thanks!

[haiyuan-eng-google]

Is this needed?

Does it work if we always omit location, and bq client can resolve the location?

[caohy1988]

Is this needed? Does it work if we always omit location, and bq client can resolve the location?

You're right — the explicit location= pass is unnecessary. I traced the full call chain in the BQ Python client:

1. client.query(sql) — when location param is omitted, falls back to self.location (client.py:89-90)
2. Since we now create bigquery.Client(project=..., credentials=...) without location, self.location is None
3. _to_query_request() — when location is None, the "location" key is not included in the API request body (_job_helpers.py:35-36)
4. The BQ API receives a request with no location field and infers location from the dataset referenced in the CREATE OR REPLACE VIEW DDL

So the simplest fix is just removing location=self.location from the bigquery.Client() constructor — which this PR already does. The _resolved_location / get_dataset() machinery is unnecessary overhead.

I'll simplify: remove _resolved_location, the get_dataset() call, and the explicit location= in client.query(). The only production change becomes removing location=self.location from the bigquery.Client() constructor.