Refactor elasticsearch scaler config

[rickbrouwer]

• Refactor the scaler to match the new metadata guidelines.
• Because i deleted const defaultUnsafeSsl = false in the elasticseach_scaler.go, kafka_scaler.go is giving error pkg/scalers/kafka_scaler.go:354:19: undefined: defaultUnsafeSsl. That's why I added the const in kafka_scaler.go.
• Extra check if both username and password are provided when addresses is used (also test added).
• Made a new splitWithSeparator function so the separator is configurable.
• The documentation states that the field index is comma separated. In the code it is semicolon. There is a separate PR created in the keda-docs repo (1465).

Checklist

• I have verified that my change is according to the deprecations & breaking changes policy
• Tests have been added
• A PR is opened to update the documentation on (repo) (if applicable)
• Commits are signed with Developer Certificate of Origin (DCO - learn more)

Related: 5797
Docs: 1465

[rickbrouwer]

Hi @wozniakjan

I've also refactored the Elasticsearch scaler to match the new metadata guidelines. This one needs a good look at the code 🙏

This because TypedConfig support slices, but only the elemSeparator accepts ",". So i added code so you can also slice on more separators like ";" (another option is to add a new field tag parameter like separator so you can choose. That will probably create some rework for already refactored scalers, but i like to hear your opinion).

[wozniakjan]

thank you, very well done!

ptal @kedacore/keda-core-contributors

[zroubalik]

Looking good, could you please resolve the config? then we are good to merge this one. Thanks

[rickbrouwer]

Looking good, could you please resolve the config? then we are good to merge this one. Thanks

Done :) Can you also run the run-e2e run for elasticsearch?