chore(python): block pushing non-cloud docs to Cloud RAD (#412)

Source-Link: googleapis/synthtool@694118b
Post-Processor: gcr.io/cloud-devrel-public-resources/owlbot-python:latest@sha256:ec49167c606648a063d1222220b48119c912562849a0528f35bfb592a9f72737

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

.coveragerc

@@ -18,6 +18,7 @@
 [run]
 branch = True
 omit =
+  google/__init__.py
   google/cloud/__init__.py
 
 [report]

.github/.OwlBot.lock.yaml

@@ -1,3 +1,3 @@
 docker:
   image: gcr.io/cloud-devrel-public-resources/owlbot-python:latest
-  digest: sha256:979d9498e07c50097c1aeda937dcd32094ecc7440278a83e832b6a05602f62b6
+  digest: sha256:ec49167c606648a063d1222220b48119c912562849a0528f35bfb592a9f72737

.kokoro/docs/common.cfg

@@ -30,7 +30,9 @@ env_vars: {
 
 env_vars: {
     key: "V2_STAGING_BUCKET"
-    value: "docs-staging-v2"
+    # Push non-cloud library docs to `docs-staging-v2-staging` instead of the
+    # Cloud RAD bucket `docs-staging-v2`
+    value: "docs-staging-v2-staging"
 }
 
 # It will upload the docker image after successful builds.