ci: use actual main branch for components repo unit test job (angular#46743)

For the branch rename migration we temporarily had to work
from a forked-off branch. Now that all the migration and cleanup
Is complete, we can switch to the actual new main branch.

This is the last remaining cleanup in the organization as it seems.
PR Close angular#46743

Author: devversion

.circleci/env.sh

@@ -72,7 +72,7 @@ setPublicVar SAUCE_READY_FILE_TIMEOUT 120
 setPublicVar COMPONENTS_REPO_TMP_DIR "/tmp/angular-components-repo"
 setPublicVar COMPONENTS_REPO_URL "https://github.com/angular/components.git"
 # TODO(BRANCH_RENAME_CLEANUP): fixup branch name to point to main branch
-setPublicVar COMPONENTS_REPO_BRANCH "main-branch-rename-do-not-delete"
+setPublicVar COMPONENTS_REPO_BRANCH "main"
 # **NOTE**: When updating the commit SHA, also update the cache key in the CircleCI `config.yml`.
 setPublicVar COMPONENTS_REPO_COMMIT "7a24e95bafbdeb697f74a48e275c2442bcbefc74"