build: lock material unit tests job to specific commit (#31569)

No longer locks the Material unit tests job to a specific branch, but rather allows
locking to a specific commit from a given branch. This allows us to use the
"master" branch from the `components` repository.

PR Close #31569

scripts/ci/clone_angular_material_repo.sh

@@ -2,9 +2,30 @@
 
 set -u -e -o pipefail
 
-# Ensure that the temporary directory does not exist.
-rm -rf ${MATERIAL_REPO_TMP_DIR}
+# Clones the Angular Material repository if the repository has not been cloned before. If
+# the repository is already cloned, the script refreshes the repository by syncing with
+# upstream and resetting to the desired Material commit (see "MATERIAL_REPO_COMMIT" variable).
 
-# Clone the Material repository into the given temporary directory.
-git clone --depth 1 --branch ${MATERIAL_REPO_TAG} ${MATERIAL_REPO_URL} \
-  ${MATERIAL_REPO_TMP_DIR}
+if [[ ! -d "${MATERIAL_REPO_TMP_DIR}" ]]; then
+  # Clone the Material repository if not present through restored cache.
+  git clone --branch ${MATERIAL_REPO_BRANCH} ${MATERIAL_REPO_URL} ${MATERIAL_REPO_TMP_DIR}
+
+  # Switch into the cloned repository.
+  cd ${MATERIAL_REPO_TMP_DIR}
+
+  # Reset branch to the desired commit.
+  git reset --hard ${MATERIAL_REPO_COMMIT}
+else
+  # Switch into the cached repository.
+  cd ${MATERIAL_REPO_TMP_DIR}
+
+  # Only refresh the repository if the current branch HEAD is not
+  # matching the desired commit.
+  if [[ "$(git rev-parse HEAD)" != "${MATERIAL_REPO_COMMIT}" ]]; then
+    # Pull the latest changes of the specified branch.
+    git fetch origin ${MATERIAL_REPO_BRANCH}
+
+    # Reset the current branch to the desired commit.
+    git reset --hard ${MATERIAL_REPO_COMMIT}
+  fi
+fi