test(bigquerystorage): create sessions using await() to address flakiness

[whowes]

Recurring test flakes (#11964, #12981) have resulted when metadata for tables created via bigquery.googleapis.com are not immediately available for reading via bigquerystorage.googleapis.com. This PR introduces Awaitility to bigquerystorage and uses it in the flaky ITBigQueryStorageTest classes to retry creating ReadSessions when they fail with NotFoundExceptions.

Fixes #11964

[gemini-code-assist]

Code Review

This pull request adds the Awaitility library as a test dependency and updates the integration tests in both v1beta1 and v1beta2 versions of ITBigQueryStorageTest to poll for read session creation while ignoring NotFoundException. The review feedback suggests using the fully qualified java.time.Duration class name in the await() blocks to prevent potential compilation conflicts with other commonly imported Duration classes.

[gemini-code-assist]

To prevent potential compilation errors due to class name conflicts (e.g., with com.google.protobuf.Duration or org.threeten.bp.Duration which are commonly imported in client library tests), it is safer to use the fully qualified java.time.Duration class name.

Suggested change

	ReadSession session =
	await()
	.atMost(Duration.ofSeconds(30))
	.pollInterval(Duration.ofSeconds(1))
	.ignoreException(NotFoundException.class)
	.until(() -> client.createReadSession(request), Objects::nonNull);
	ReadSession session =
	await()
	.atMost(java.time.Duration.ofSeconds(30))
	.pollInterval(java.time.Duration.ofSeconds(1))
	.ignoreException(NotFoundException.class)
	.until(() -> client.createReadSession(request), Objects::nonNull);

[gemini-code-assist]

To prevent potential compilation errors due to class name conflicts (e.g., with com.google.protobuf.Duration or org.threeten.bp.Duration which are commonly imported in client library tests), it is safer to use the fully qualified java.time.Duration class name.

Suggested change

	ReadSession session =
	await()
	.atMost(Duration.ofSeconds(30))
	.pollInterval(Duration.ofSeconds(1))
	.ignoreException(NotFoundException.class)
	.until(() -> client.createReadSession(request), Objects::nonNull);
	ReadSession session =
	await()
	.atMost(java.time.Duration.ofSeconds(30))
	.pollInterval(java.time.Duration.ofSeconds(1))
	.ignoreException(NotFoundException.class)
	.until(() -> client.createReadSession(request), Objects::nonNull);