librem5: Use playbin3 whenever possible

This has the potential to confuse applications
(see fd294179)
so apps should opt in themselves when possible.
4 jobs for use-playbin3 in 3 minutes and 57 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Package
passed #352460
librem5
package-pureos-byzantium

00:00:51

passed #352461
librem5:arm64
package-pureos-byzantium:arm64

00:02:52

 
  Test Package
passed #352462
librem5
autopkgtest-pureos-byzantium-package

00:03:03

passed #352463
librem5
lintian-pureos-byzantium-package

00:00:46