chore: update ownership/routing for repo (#1287)

This PR effectively moves ownership for this repo to the python language
team, and removes api-bigquery as the defacto code owner.

Author: shollyman

.github/CODEOWNERS

@@ -6,7 +6,7 @@
 # Note: This file is autogenerated. To make changes to the codeowner team, please update .repo-metadata.json.
 
 # @googleapis/yoshi-python @googleapis/api-bigquery are the default owners for changes in this repo
-*     @googleapis/yoshi-python @googleapis/api-bigquery
+*     @googleapis/yoshi-python @googleapis/python-core-client-libraries
 
 # @googleapis/python-samples-reviewers @googleapis/api-bigquery are the default owners for samples changes
-/samples/   @googleapis/python-samples-reviewers @googleapis/api-bigquery
+/samples/   @googleapis/python-samples-reviewers @googleapis/python-core-client-libraries

.github/blunderbuss.yml

@@ -4,14 +4,14 @@
 # Note: This file is autogenerated. To make changes to the assignee
 # team, please update `codeowner_team` in `.repo-metadata.json`.
 assign_issues:
-  - googleapis/api-bigquery
+  - googleapis/python-core-client-libraries
 
 assign_issues_by:
   - labels:
       - "samples"
     to:
       - googleapis/python-samples-reviewers
-      - googleapis/api-bigquery
+      - googleapis/python-core-client-libraries
 
 assign_prs:
-  - googleapis/api-bigquery
+  - googleapis/python-core-client-libraries

.repo-metadata.json

@@ -9,5 +9,5 @@
     "distribution_name": "sqlalchemy-bigquery",
     "api_id": "bigquery.googleapis.com",
     "default_version": "",
-    "codeowner_team": "@googleapis/api-bigquery"
+    "codeowner_team": "@googleapis/python-core-client-libraries"
 }