Gitlab-ci: Set a cache policy that isolates each job.

6 jobs for <span class="ref-name">custom-registry</span> in 7 minutes and 39 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #9125
fedora:test

00:01:27

 
  Lint
manual #9127
allowed to fail manual
clippy
manual #9126
allowed to fail manual
rustfmt
 
  Distro Test
passed #9130
debian:testing

00:04:49

passed #9128
fedora:rawhide

00:04:34

passed #9129
opensuse:tumbleweed

00:06:11