[CT-2185] [Bug] 502 BadGateway error should retry

[patkearns10]

Is this a new bug in dbt-bigquery?

• I believe this is a new bug in dbt-bigquery
• I have searched the existing issues, and I could not find an existing issue for this bug

Current Behavior

User experiences intermittent failure on a job. Some runs are just fine, and occasionally one will error out with below:

Unable to generate access token, if you're using impersonate_service_account, make sure your initial account has the "roles/iam.serviceAccountTokenCreator" role on the account you are trying to impersonate.

and

14:03:39      <a href=//www.google.com/><span id=logo aria-label=Google></span></a>
14:03:39      <p><b>502.</b> <ins>That's an error.</ins>
14:03:39      <p>The server encountered a temporary error and could not complete your request.<p>Please try again in 30 seconds.  <ins>That's all we know.</ins>

Expected Behavior

The error itself says to retry in 30 seconds, so we should add this to the retry logic so that it happens automatically.

Steps To Reproduce

It is very intermittent, so unable to reproduce on my end.

Relevant log output

Unable to generate access token, if you're using impersonate_service_account, make sure your initial account has the "roles/iam.serviceAccountTokenCreator" role on the account you are trying to impersonate.

and

14:03:39      <a href=//www.google.com/><span id=logo aria-label=Google></span></a>
14:03:39      <p><b>502.</b> <ins>That's an error.</ins>
14:03:39      <p>The server encountered a temporary error and could not complete your request.<p>Please try again in 30 seconds.  <ins>That's all we know.</ins>

Environment

- OS:
- Python:
- dbt-core: 1.3
- dbt-bigquery: 1.3

Additional Context

ticket: https://dbtcloud.zendesk.com/agent/tickets/42996

dbt-bigquery/dbt/adapters/bigquery/connections.py

Lines 51 to 56 in edca37a

	RETRYABLE_ERRORS = (
	google.cloud.exceptions.ServerError,
	google.cloud.exceptions.BadRequest,
	ConnectionResetError,
	ConnectionError,
	)

does not have the BadGateway 502 in the list of retryable cases and it probably should.
see: https://googleapis.dev/python/google-api-core/latest/exceptions.html

related, but not the same:
#263 (not retried during job timeout)
#231 (larger piece on refactoring bq retries).

[dbeatty10]

@patkearns10 thanks for documenting this issue and opening a PR to fix it! 🤩