Add Leader Election Lease Options

[wsugarman]

Add new options for configuring the leader election lease, including:

• KEDA_OPERATOR_LEADER_ELECTION_LEASE_DURATION
• KEDA_OPERATOR_LEADER_ELECTION_RENEW_DEADLINE
• KEDA_OPERATOR_LEADER_ELECTION_RETRY_PERIOD
• KEDA_METRICS_LEADER_ELECTION_LEASE_DURATION
• KEDA_METRICS_LEADER_ELECTION_RENEW_DEADLINE
• KEDA_METRICS_LEADER_ELECTION_RETRY_PERIOD

Checklist

• Commits are signed with Developer Certificate of Origin (DCO - learn more)
• Tests have been added
• A PR is opened to update our Helm chart (repo)
  • Skipped because these values are new environment variables that may be configured through the existing env element
• A PR is opened to update the documentation on (repo) (if applicable)
• Changelog has been updated and is aligned with our changelog requirements

Relates to #2836
Relates to kedacore/keda-docs#842

[wsugarman]

I am unsure if this should result in new documentation

[zroubalik]

I am unsure if this should result in new documentation

Yeah, we should cover this in this section of docs: https://keda.sh/docs/2.8/operate/cluster/

Thanks!

[wsugarman]

Taking another look, perhaps there are too many options and it's better to simply share the same values for both the operator and metrics server?

[zroubalik]

yeah, it's a lot of new values, but I think that it is okay to keep it like this :)

[zroubalik]

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

[zroubalik]

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

[wsugarman]

@zroubalik Thank you for your help!