glamor/glxprov: Stop exposing non-db(-capable) configs

4 jobs for dix-glxegl in 1 minute and 38 seconds (queued for 3 seconds)
latest
Name Stage Failure
failed
meson Build And Test
files in cache                     93078
cache size 4.6 GB
max cache size 5.0 GB
Uploading artifacts for failed job
Uploading artifacts...
WARNING: build/test/piglit-results/: no matching files
ERROR: No files to upload
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1

failed
meson-noglamor Build And Test
files in cache                     91460
cache size 4.5 GB
max cache size 5.0 GB
Uploading artifacts for failed job
Uploading artifacts...
WARNING: build/test/piglit-results/: no matching files
ERROR: No files to upload
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1