Refine some details for the github actions update

Set the retention-days variable to 14 days for these artifacts:
- the zloop error logs
- the zloop vdev files
- the compiled modules

Add the abality to re-run some part of the functional testings.
Fix some comments and remove the deleting of the modules artifact.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tino Reichardt <milky-zfs@mcmilk.de>
Closes #14637

.github/workflows/zfs-linux-tests.yml

@@ -41,6 +41,7 @@ jobs:
         path: |
           /var/tmp/zloop/*/
           !/var/tmp/zloop/*/vdev/
+        retention-days: 14
         if-no-files-found: ignore
     - uses: actions/upload-artifact@v3
       if: failure()
@@ -48,6 +49,7 @@ jobs:
         name: Zpool-files-${{ inputs.os }}
         path: |
           /var/tmp/zloop/*/vdev/
+        retention-days: 14
         if-no-files-found: ignore
 
   sanity: