Blacklist logging GTK warning about null action targets

GAction does not support disabling parameterised actions
with specific values, but GTK complains if the parameter is
set to null to achieve the same effect, and they aren't
interested in supporting that: gtk!1151

Move GDKPixbuf blacklisting to log handler as well, target it more
precisely.
3 jobs for mjog/misc-fixes in 16 minutes and 3 seconds (queued for 1 second)
Status Job ID Name Coverage
  .Pre
passed #521365
flatpak

00:09:14

 
  Build
passed #521366
fedora

00:06:48

passed #521367
ubuntu

00:03:35