Revert the changes to add an entryoint.sh script
This change didn't work because it was incomplete. I had added the script, but failed to change the entrypoint itself.
Irrespective of this, we are reverting the change because we actually need to run the driver-registrar container as root, which means that we no longer have to support g+w privileges on the unix socket created by the cephcsi plugin.
Bug: T327259