roles/common/tasks/rhel-entitlements.yml: check for /var/lib/dbus

roles/common/tasks/rhel-entitlements.yml: check for /var/lib/dbus

dbus-uuidgen will only work if /var/lib/dbus already exists.
In RHEL 9.3, 1) dbus-uuidgen isn't even installed (from
dbus-tools), and 2) /var/lib/dbus does not exist unless
dbus-daemon is installed, which it's not, by default, for a
kickstart install.  So this role will break when run during
fog image capture.

Change to do the two dbus-uuidgen's only if /var/lib/dbus exists.

Signed-off-by: Dan Mick <dmick@redhat.com>