Disable EESSI tests in CI and make them debuggable

[sjpb]

EESSI tests are randomly failing in CI most of the time with

TASK [Run test job] ************************************************************
task path: /home/runner/work/ansible-slurm-appliance/ansible-slurm-appliance/ansible/ci/check_eessi.yml:30
fatal: [ci5747728207-login-0]: UNREACHABLE! => {
    "changed": false,
    "unreachable": true
}

MSG:

Data could not be sent to remote host "10.0.4.25". Make sure this host can be reached over ssh: 

The host is reachable, and nothing shows in logs to drop the connection. They work fine when run against a cluster manually.

This PR disables these tests in CI, and changes the test to run via sbatch so that test output is available (via Ansible output on success, or via ssh to the cluster if Ansible fails).

[sjpb]

Note c91c8ed above passed CI twice, but it takes a long time (1h55,1h45).

[sjpb]

054d287 failed in EESII tests, as before

[sd109]

LGTM for now, let me know if I can help with debugging the underlying issue later down the line.