Ingress deletion by label instead of name

[kaiivoschneider]

Summary

The Mattermost operator keeps deleting Ingresses it did not create itself if they have the same name. It makes more sense for the operator to find resources by their labels. That is what Kubernetes labels are for.

Release Note

NONE

[mm-cloud-bot]

@kaiivoschneider: Adding the "do-not-merge/release-note-label-needed" label because no release-note block was detected, please follow our release note process to remove it.

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