Tests

Switch to external composefs #1948

Job	Run time
Build (Fedora)	48s
Build (C9S)	1m 34s
build-integration	4m 8s
Code style	37s
Build - FCOS minimal	1m 35s
Debian Stable with sign-ed25519 and FUSE 2	7m 42s
Debian Stable with curl, sign-ed25519, no gpgme, FUSE 3	7m 5s
Debian Stable 32 bit	7m 36s
Debian Stable without libsystemd	7m 2s
Debian Testing	7m 45s
Debian Testing with libsoup3	6m 50s
Debian stable + static-prepareroot	7m 15s
Ubuntu Latest Release	7m 4s
Privileged testing	0s
	1h 7m 1s

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