revert(network-manager): avoid restarting NetworkManager

revert(network-manager): avoid restarting NetworkManager

This reverts commit 77630365aed201a729c73a9ffda0733a75f3fee4.

Its commit message states:

  On EL8.3 the NetworkManager keep restarting even if it exits successfully
  while waiting for Clevis to unlock. This patch ensures NetworkManager runs
  only once in initrd.

Yes; NetworkManager is run multiple times, so that it's able to
configure interfaces that haven't been seen previously (because bus was
slow to scan or device took time to initialize).

It's not clear what problem was the original commit trying to fix.
I suspect there was no problem, just a misunderstanding.