Revert "Switch coverage CI targets to EngFlow (#39269)" (#39299)

Commit Message:

This reverts commit e0420ee. It
unexpectedly resulted in lower coverage numbers - we should rollback
while we are investigating what's going on to avoid disruptions.

Additional Description:

Some relevant discussions can be found in
#39030 which prompted me to work
on this in the first place. And I will use
#39248 as a tracking bug for
the coverage changes.

Signed-off-by: Mikhail Krinkin <[email protected]>

Author: krinkinmu

.github/workflows/_check_coverage.yml

@@ -38,7 +38,7 @@ jobs:
     uses: ./.github/workflows/_run.yml
     name: ${{ matrix.name ||matrix.target }}
     with:
-      bazel-extra: '--config=remote-envoy-engflow'
+      # bazel-extra: '--config=remote-envoy-engflow'
       cache-build-image: ${{ fromJSON(inputs.request).request.build-image.default }}
       concurrency-suffix: -${{ matrix.target }}
       diskspace-hack: ${{ matrix.diskspace-hack && true || false }}
@@ -50,6 +50,7 @@ jobs:
         lower than limit
       gcs-cache-bucket: ${{ inputs.gcs-cache-bucket }}
       rbe: true
+      rbe-google: true
       request: ${{ inputs.request }}
       runs-on: ${{ fromJSON(inputs.request).config.ci.agent-ubuntu }}
       steps-post: |