qtdemux: Allow a sample for multple output streams

A sample of meta item (such as an image) can be also other stream's sample.
18 jobs for heif-support in 28 minutes and 58 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Preparation
passed #236414
gst indent

00:00:43

passed #236413
manifest

00:00:51

 
  Build
passed #236415
build fedora x86_64

00:04:50

passed #236416
build nodebug fedora x86_64

00:03:50

 
  Test
passed #236443
check fedora

00:03:01

failed #237005
integration testsuites fedora

00:20:14

failed #236417
check fedora

00:08:45

failed #236446
integration testsuites fedora

00:20:43

failed #236445
integration testsuites fedora

00:20:01

failed #236444
integration testsuites fedora

00:07:50

failed #236418
integration testsuites fedora

00:14:51

 
  Full Builds
skipped #236420
build cerbero android universal
skipped #236421
build cerbero cross win32
skipped #236422
build cerbero cross win64
skipped #236419
build cerbero fedora x86_64
 
  Full Tests
skipped #236424
valgrind bad
skipped #236423
valgrind good
 
  Apps
skipped #236425
android universal examples
 
Name Stage Failure
failed
integration testsuites fedora Test
           Total: 1327
Uploading artifacts...
gst-build/build/meson-logs/: found 2 matching files
validate-logs: found 53538 matching files
Uploading artifacts to coordinator... ok id=237005 responseStatus=201 Created token=xzvqHxUC
Uploading artifacts...
validate-logs/*.xml: found 1 matching files
Uploading artifacts to coordinator... ok id=237005 responseStatus=201 Created token=xzvqHxUC
ERROR: Job failed: exit code 1