Use creds in alternator tests

[Michal-Leszczynski]

This PR does a few things:

• it enforces authentication on alternator queries (https://github.com/scylladb/scylla-enterprise/issues/4708)
• it uses creds for authenticating alternator API in pkg tests (Alternator enterprise tests are failing #4032)
• it replaces alternator query ping with simple ping when authentication is enforced (SM can't make alternator query ping when authorization is required #4036)

Fixes #4032
Ref https://github.com/scylladb/scylla-enterprise/issues/4708
Ref #4036

[Michal-Leszczynski]

@karol-kokoszka This PR is ready for review!
Please take a look at issues https://github.com/scylladb/scylla-enterprise/issues/4708 and #4036 as well.

[Michal-Leszczynski]

@karol-kokoszka there are other PRs rebased on this one, could you take a look, so that they can be unblocked as well?

[karol-kokoszka]

Thanks !

[Michal-Leszczynski]

Here is some proof that this fixes the result observed here:

miles@fedora:~/scylla-manager$ ./sctool.dev status -c myc
Datacenter: dc1
╭────┬────────────┬──────────┬──────────┬────────────────┬──────────┬──────┬─────────┬────────┬──────────┬──────────────────────────────────────╮
│    │ Alternator │ CQL      │ REST     │ Address        │ Uptime   │ CPUs │ Memory  │ Scylla │ Agent    │ Host ID                              │
├────┼────────────┼──────────┼──────────┼────────────────┼──────────┼──────┼─────────┼────────┼──────────┼──────────────────────────────────────┤
│ UN │ UP (1ms)   │ UP (5ms) │ UP (1ms) │ 192.168.200.11 │ 2h39m18s │ 16   │ 31.069G │ 6.0.1  │ Snapshot │ e7240eff-d6ef-4972-a137-d5bad1d6a02c │
│ UN │ UP (1ms)   │ UP (5ms) │ UP (1ms) │ 192.168.200.12 │ 2h39m18s │ 16   │ 31.069G │ 6.0.1  │ Snapshot │ a78f1f32-c3f5-4497-bfcb-95101599970b │
│ UN │ UP (1ms)   │ UP (5ms) │ UP (3ms) │ 192.168.200.13 │ 2h39m18s │ 16   │ 31.069G │ 6.0.1  │ Snapshot │ 103304a2-6df0-4da3-9bc6-4cf8a83f43ec │
╰────┴────────────┴──────────┴──────────┴────────────────┴──────────┴──────┴─────────┴────────┴──────────┴──────────────────────────────────────╯