online-accounts: Complete account removal in cc_goa_panel_finalize()

When removing an online account, gnome-control-center gives the user
the possibility to undo the action showing an "undo notification".
Right now if you close the gnome-control-center window, without dismissing
the notification, the online account will not be properly removed.

GNOME/gnome-control-center#25
2 jobs for remove-account-on-finalize in 21 minutes and 43 seconds (queued for 43 seconds)
latest
Status Name Job ID Coverage
  Build
passed build #19321

00:11:04

 
  Test
passed test #19322

00:10:38