fix(bigquery-jdbc): fix getExportedKeys SQL and add TPC metadata tests

[keshavdandeva]

b/543942439

Changes

• DatabaseMetaData_GetExportedKeys.sql: Updated SQL to use `%1$s`.`%2$s`.INFORMATION_SCHEMA.<VIEW>
• ITTPCBigQueryTest.java: Added testDatabaseMetadataOperationsInTPC() and added null checks for ENDPOINT_URL, UNIVERSE_DOMAIN, and auth environment variables.

Verification

• Verified ITTPCBigQueryTest#testDatabaseMetadataOperationsInTPC against live TPC project tpczero-system:bigquery-drivers on apis-tpczero.goog

[gemini-code-assist]

Code Review

This pull request updates the SQL query for retrieving exported keys to correctly use backticks for catalog and schema names, and adds null checks to environment variable validations in the integration tests. Additionally, a new integration test is introduced to verify various database metadata operations. The feedback highlights a potential resource leak where the database connection is not safely closed if an exception is thrown during statement creation, suggesting the use of try-with-resources.

[logachev]

Actually this file is not used, I need to remove it after validating that there are no unique tests.

We're running regular set of tests in TPC. We should have regular metadata test validating this scenario

[keshavdandeva]

The getExportedKeys SQL works without this change. The new tests would be redundant as the plan is to delete the ITTPCBigQueryTest.java file and use existing ITs in TPC env. Thus, closing this PR.