Clear out service disabled reason on enable

When a service gets re-enabled, clear out the 'disabled_reason' column.

Fix bug 1197423.

Change-Id: I78c9e40c65e96fbc6eff0e3426cfd87b0810cd69
Merge "Clear out service disabled reason on enable"
Merge remote-tracking branch 'm_src_repo/citrix-fixes' into build-temp