Remove impersonation lifetime. (#882)

* Remove impersonation lifetime.

Per #769 , we shouldn't
need to set the lifetime of an impersonated token. In some edge cases,
attempting to set it to the job execution timeout (> 300 seconds) can
result in authentication failures, even though the job will complete
successfully and authentication creds will be correctly refreshed.

* Changie data.

---------

Co-authored-by: Doug Beatty <44704949+dbeatty10@users.noreply.github.com>
Co-authored-by: Mike Alfare <13974384+mikealfare@users.noreply.github.com>

.changes/unreleased/Fixes-20230817-095527.yaml

@@ -0,0 +1,6 @@
+kind: Fixes
+body: Avoid setting lifetime on impersonation tokens.
+time: 2023-08-17T09:55:27.333914673-04:00
+custom:
+  Author: cmc333333
+  Issue: "769"

dbt/adapters/bigquery/connections.py

@@ -356,7 +356,6 @@ def get_impersonated_credentials(cls, profile_credentials):
             source_credentials=source_credentials,
             target_principal=profile_credentials.impersonate_service_account,
             target_scopes=list(profile_credentials.scopes),
-            lifetime=(profile_credentials.job_execution_timeout_seconds or 300),
         )
 
     @classmethod