Allow overriding Scylla command line args

[PenguinToast]

Description of your changes:

Allow scyllaArgs to replace existing Scylla command line arguments. This is necessary to override the hardcoded 0.0.0.0 listen address to :: when we want to use IPv6.

Which issue is resolved by this Pull Request: Resolves #

[tnozicka]

could we just always use :: to listen to both stacks?

[PenguinToast]

could we just always use :: to listen to both stacks?

I believe there are systems where listening on :: doesn't also listen on 0.0.0.0, so just listening on :: for those would break IPv4 communication

[PenguinToast]

@tnozicka let me know what you think ^

[scylla-operator-bot[bot]]

PR needs rebase.

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