feat: Support using connection strings for Event Hub namespace instead of the Event Hub itself.

[v-shenoy]

Provide a description of what has been changed

Checklist

• Commits are signed with Developer Certificate of Origin (DCO - learn more)
• Tests have been added
• A PR is opened to update the documentation on (repo) (if applicable)
• Changelog has been updated and is aligned with our changelog requirements

Fixes #3922

Relates to kedacore/keda-docs#988

[JorTurFer]

LGTM!
I think we need to update docs as well because eventHubName is optional and only required in case of pod identity , but now it could be also required with we use namespace connection string instead of eh connection string

[v-shenoy]

LGTM! I think we need to update docs as well because eventHubName is optional and only required in case of pod identity , but now it could be also required with we use namespace connection string instead of eh connection string

Haha, was in the middle of doing it.

[JorTurFer]

/run-e2e event*
Update: You can check the progress here