T5141: Add numbers for dhclient-exit-hooks.d to enforce order

Add numbers for all dhclient-exit-hooks.d to enforce script order execution
Also, move '99-run-user-hooks' to '98-run-user-hooks' due to
vyatta-dhclient-hook bug and exit with 'exit 1' it is
described in the https://vyos.dev/T4856, so we should move this hook
to the end. Rename 'vyatta-dhclient-hook' to '99-vyatta-dhclient-hook'