Enable use of uniqe tls passwords pr host

[ivareri]

Allow use of unique elasticsearch_tls_key_passphrase pr host

(not sure if this is a fix or a feature, but I went with fix as that's the behaviour I expected)

[widhalmt]

Hm... it seems like the hostvars variant of a variable does not fall back to a group var when it's not set. Shouldn't the current code already be able to use per host passwords?

[ivareri]

Hum, my understanding was that hostvars should include everything as the host would see it, including group_vars. I guess I'll do some testing.

The problem I'm trying to fix is caused by the certificate generation loop only running when inventory_hostname == elasticstack_ca. The current code therefore uses the elasticsearch_tls_key_passphrase for the ca host when generating the certs. It does however use the proper elasticsearch_tls_key_passphrase when configuring the nodes. This leaves a broken install on every node but elasticstack_ca, as the password set in the configuration does not match the password used when generating the certificate.

[ivareri]

Apparently there are 3 variable scopes in Ansible, and hostvars only covers one of them by design.

I've fixed the PR so it uses the variable from hostvars if it is set, otherwise it will fallback to the current behavior.

[widhalmt]

Thanks! Let's see what the tests are saying. :-)

[widhalmt]

Great. Could please just fix the linter findings?

[ivareri]

Fixed linting.

Note: This PR also changes one of the molecule scenarios in order to fully test the implemented fix

[widhalmt]

Yes, thank you! This looks like a great addidtion.