group: Use proper group constructor

Otherwise we might en up having a group which is not backed by any asset
leading to possible assertion as this should never happen (see
https://gitlab.gnome.org/GNOME/pitivi/-/issues/2526)

Part-of: <gstreamer/gst-editing-services!232>
32 jobs for !232 with fix_group_creation in 29 minutes and 30 seconds (queued for 7 seconds)
detached
Status Job ID Name Coverage
  Build Docker
passed #7811656
alpine amd64 manifest builder docker

00:00:21

passed #7811655
android docker

00:00:31

passed #7811654
cerbero fedora amd64 docker

00:00:18

passed #7811653
fedora amd64 docker

00:00:18

passed #7811657
gst-indent amd64 docker

00:00:12

passed #7811658
windows shell 1809
windows amd64 docker

00:00:08

 
  Preparation
passed #7811661
check allow-edit

00:00:09

passed #7811660
gst indent

00:00:11

passed #7811659
manifest

00:00:27

 
  Build
passed #7811670
gstreamer
build cerbero cross-android universal

00:12:10

passed #7811674
gst-ios-14.3
build cerbero cross-ios universal

00:20:01

passed #7811671
gstreamer
build cerbero cross win32

00:08:58

passed #7811672
gstreamer
build cerbero cross win64

00:04:38

passed #7811669
gstreamer
build cerbero fedora x86_64

00:06:01

passed #7811673
gst-macos-11.1
build cerbero macos x86_64

00:15:40

passed #7811675
docker windows 1809 gstreamer-windows
build cerbero msvc x86_64

00:14:36

passed #7811665
build clang fedora x86_64

00:09:48

manual #7811668
docker windows 1809 allowed to fail manual
build msys2
passed #7811662
build nodebug fedora x86_64

00:07:12

passed #7811663
build static fedora x86_64

00:09:21

passed #7811664
build static nodebug fedora x86_64

00:06:58

passed #7811666
docker windows 1809
build vs2017 amd64

00:16:17

passed #7811667
docker windows 1809
build vs2017 x86

00:16:41

 
  Test
passed #7811676
gstreamer
check fedora

00:07:15

passed #7811677
gstreamer
integration testsuites fedora 1/4

00:16:57

passed #7811678
gstreamer
integration testsuites fedora 2/4

00:16:23

passed #7811679
gstreamer
integration testsuites fedora 3/4

00:15:53

passed #7811680
gstreamer
integration testsuites fedora 4/4

00:15:25

passed #7811681
gstreamer
valgrind ges

00:07:33

 
  Integrate
passed #7811682
cross-android universal examples

00:06:30

passed #7811684
gst-ios-14.3
cross-ios universal examples

00:04:31

passed #7811683
documentation

00:15:42