Add a rebuild nonce to the charm-keystone-ldap charm the same
as other reactive charms. This allows the charm to trigger a
rebuild when upstream dependencies need to be synced into a
reactive charm.
This sync will pull in a change for parsing config flags that
will ensure the ordering is consistent each time the config
flag parsing is executed (even across hook invocations).
Change-Id: I4a4b58a2176314b69c577810a9e15d0814e24ae5
Closes-Bug: #1698343
92f0fb511d