parse: Move variable to block where it's used

There was a dead assignment used outside of the bin/pipeline creation
which was confusing (and unused). Just move that variable to
where it is actually used.

(Note that that variable was not needed outside of that block since
the refactoring done in 2b33d331 )
6 jobs for scanbuild-cleanups in 30 minutes and 43 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Preparation
passed #64171
gst indent

00:00:30

passed #64170
manifest

00:00:22

 
  Build
passed #64172
build fedora x86_64

00:03:09

 
  Test
passed #64173
check fedora

00:14:21

 
  Full Builds
passed #64174
build android arm64 api28

00:03:03

passed #64175
build cerbero fedora x86_64

00:10:17