fix: for BigQuery.V2, Storage.V1, DataStore.V1, Firestore

[robertvoinescu-work]

Fixes the following:

• BigQuery Timestamp Parsing:

  • Issue: The default value for UseInt64Timestamp should default to true in the client during stateless query optimization, otherwise we get the service default of not using Int64Timestamps
    System.FormatException: The input string '1.48709313E9' was not in a correct format.
  • Fix: Default UseInt64Timestamp to true.

• Firestore & Datastore Database Index Timeouts:

  • Issue: Index creation is exceeding the default 5-minute polling limit during fixture setup:
    System.TimeoutException: Operation did not complete within the specified expiry time
  • Fix: Increased polling timeouts in FirestoreFixture and DatastoreFixture to accommodate slower backend indexing.

• Storage.V1 State Consistency:

  • Issue: ResumeWithPageToken failed due to an unexpected object count in the shared ReadBucket:
    Assert.Equal() Failure: Values differ` <br> `Expected: 6` <br> `Actual: 7
  • Fix: Moved context-based tests to a separate bucket to prevent mutating the read-only ReadBucket.

  Validations

  The corresponding integration and unit tests have been run and successfully pass now.

  b/502217142

[gemini-code-assist]

Code Review

This pull request updates the BigQuery client to ensure UseInt64Timestamp is correctly propagated through query options and requests, including setting a default value of true. It also increases the polling timeout for Datastore and Firestore admin operations to 10 minutes and updates Storage integration tests to use a specific bucket. Feedback includes a likely incorrect property assignment in GetQueryResultsOptions, a logic concern regarding the unconditional overwriting of FormatOptions in StatelessQueryOptions, and minor typos in a newly added comment.