Previously all Bazel repositories were cached on CircleCI
because the `experimental_repository_cache` flag has been
specified and the given repository cache directory has been
included in the CircleCI cache storage.

The directory is currently still included in the CircleCI
cache storage, but the `--repository_cache` flag is no longer
specified, and the cache directory is basically empty all the
time. The flag seems to have been removed accidentally within
SHA c8b70ae8.

We should specifiy this flag on the CI again, so that Bazel
doesn't need to install the Bazel managed node modules
all the time. This would slow down analysis phase on CI; and also
makes us dependent on the Yarn/NPM registry which often times out
if we fetch a lot of dependencies.

Also in order to make sure that cached Bazel repositories are
also most of the time in sync with what's currently defined in
the workspace, we need to update the cache key.

PR Close #28515