Remove invalid tag in GtkBuilder file

This was introduced in commit fa08a3bf
11 jobs for <span class="ref-name">privacy-invalid-gtkbuilder-tag</span> in 5 minutes and 52 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #122960
build

00:01:54

 
  Test
passed #122962
asan

00:02:10

passed #122961
test

00:01:47

 
  Manual
manual #122967
allowed to fail manual
armv8
manual #122963
allowed to fail manual
flatpak
manual #122966
allowed to fail manual
msan
manual #122968
allowed to fail manual
ppc64le
manual #122964
allowed to fail manual
tsan
manual #122965
allowed to fail manual
ubsan
 
  Review
manual #122969
allowed to fail manual
review
manual #122970
allowed to fail manual
stop_review