When purely using relation-set from a leader, updates after
the leader has changed can lead to old data being persisted
on a relation in addition to newer data being set by the new
leader. When this happens, there can be issues with services
using old data to talk to other related services.
This change introduces the use of the application data bag
to ensure that all units related to keystone get the same
data from the leader, regardless of leadership changes.
While this change enables the application data bag for these
relations, it still sends the per-unit relation data as well
to maintain backwards compatibility. Charms that consume the
identity-service and identity-notification relations will
need an update to use the application data bag to complete
this change.
Partial-Bug: #1902264
Change-Id: Iadd795fec605e7704e5a6673906452279bbecb34
9b8b81a0bc