build: Remove support for older versions of meson

Those were workarounds for versions of meson that were older than the
minimum meson version.
4 jobs for wip/hadess/meson-fixes in 1 minute and 4 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
failed #616160
debian-stable-x86_64

00:01:04

failed #616161
fedora-x86_64

00:00:51

failed #606503
debian-stable-x86_64

00:03:31

failed #606502
fedora-x86_64

00:03:53

 
Name Stage Failure
failed
debian-stable-x86_64 Build
Uploading artifacts...
WARNING: _build/config.h: no matching files
_build/meson-logs: found 2 matching files

WARNING: _build/debian-stable-x86_64-report.xml: no matching files
Uploading artifacts to coordinator... ok
id=616160 responseStatus=201 Created token=E7sJNf8m
Uploading artifacts...
WARNING: _build/debian-stable-x86_64-report.xml: no matching files
ERROR: No files to upload
ERROR: Job failed: exit code 1
failed
fedora-x86_64 Build
Uploading artifacts...
WARNING: _build/config.h: no matching files
_build/meson-logs: found 2 matching files

WARNING: _build/fedora-x86_64-report.xml: no matching files
Uploading artifacts to coordinator... ok
id=616161 responseStatus=201 Created token=9ZY8T1b6
Uploading artifacts...
WARNING: _build/fedora-x86_64-report.xml: no matching files
ERROR: No files to upload
ERROR: Job failed: exit code 1