Refactor eventing publisher default deployment specs to a configmap

[sayanh]

Description

Refactor eventing publisher env vars to a configmap so that controller does not need to set it during reconciliations.

#11256 (comment)

Reasons

Configurations should not be hard-coded.

Acceptance

• introduce a new configmap per backend

[kyma-stale-bot]

This issue has been automatically marked as stale due to the lack of recent activity. It will soon be closed if no further activity occurs. Thank you for your contributions.

[kyma-stale-bot]

This issue has been automatically marked as stale due to the lack of recent activity. It will soon be closed if no further activity occurs. Thank you for your contributions.

[k15r]

This ticket will be reevaluated once we started to discuss about a potential CRD driven EPP

[kyma-stale-bot]

This issue has been automatically marked as stale due to the lack of recent activity. It will soon be closed if no further activity occurs. Thank you for your contributions.