Mounting from sources is disabled for tests (apache#10472)

We had to enable mounting from sources for a short while
because we had to find a way to add new scripts to the
"workflow_run" workflow we have. This also requires
the apache#10470 to be merged - perf_kit to be moved to tests.utils because
it was in a separate directory and image without mounting sources
could not run the tests.

It also partially addresses the apache#10445 problem where
there was difference between sources in the image and coming
from the master. This comes from GitHub running merge on
non-conflicting changes in the PR and something that will
be addressed shortly.

The issue apache#10471 discusses this in detail.

.github/workflows/ci.yml

@@ -27,7 +27,7 @@ on:
 
 env:
 
-  MOUNT_LOCAL_SOURCES: "true"
+  MOUNT_LOCAL_SOURCES: "false"
   MOUNT_FILES: "true"
   FORCE_ANSWER_TO_QUESTIONS: "yes"
   FORCE_PULL_IMAGES: "true"