build: setup cronjob to run tests against angular snapshots (#14217)

* Sets up a cronjob workflow that runs the local browser tests against the Angular Github snapshot builds at midnight everyday.
* No longer saves cache multiple times. This can cause unexpected behavior.
* Sorts jobs in `config.yml` to group all `tests_XX` jobs.

Closes #12516.

scripts/circleci/run-local-browser-tests.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+# In case any command failed, we want to immediately exit the script with the
+# proper exit code.
+set -e
+
+# Go to project directory.
+cd $(dirname ${0})/../..
+
+# In case the "snapshot_tests" workflow is currently running this script, we
+# want to run the local browser tests against the Angular snapshot builds.
+if [[ "${CIRCLE_WORKFLOW_ID}" == "snapshot_tests" ]]; then
+  ./scripts/install-angular-snapshots.sh
+fi
+
+# Setup the test platform environment variable that will be read
+# by the Karma configuration script.
+export TEST_PLATFORM="local"
+
+# Run the unit tests on the local browsers with Karma.
+yarn gulp ci:test