network: Remove unused wifi dialog

This seems to have been copied from the connection editor code, but is not
actually used.
11 jobs for wifi-dead-dialog in 4 minutes and 44 seconds (queued for 2 seconds)
latest
Status Name Job ID Coverage
  Build
passed build #468151

00:02:20

 
  Test
passed asan #468153

00:02:23

passed test #468152

00:01:09

 
  Manual
manual armv8 #468158
allowed to fail manual
manual flatpak #468154
allowed to fail manual
manual msan #468157
allowed to fail manual
manual ppc64le #468159
allowed to fail manual
manual tsan #468155
allowed to fail manual
manual ubsan #468156
allowed to fail manual
 
  Review
manual review #468160
allowed to fail manual
manual stop_review #468161
allowed to fail manual