tests: info: Fix spurious validation

Should be equality check, not assignment.
Additionally, use fail_unless_equals_* macro for better readability
and debugging easier, if possible.
8 jobs for fix-spurious-validation in 15 minutes and 38 seconds (queued for 1 second)
Status Job ID Name Coverage
  Preparation
passed #88449
gst indent

00:00:15

passed #88448
manifest

00:00:18

 
  Build
passed #88450
build fedora x86_64

00:02:13

 
  Test
passed #88451
check fedora

00:03:57

 
  Full Builds
passed #88452
build android arm64 api28

00:03:56

passed #88454
build cerbero cross win32

00:09:09

passed #88455
build cerbero cross win64

00:05:56

passed #88453
build cerbero fedora x86_64

00:06:48