Allow you to set pod labels

[bjorns163]

The current deployment lacks the ability to set pod labels. While this may not directly affect the usage of Mattermost, it is a common feature needed in bigger environments. This adds the ability to set them

[mattermost-build]

Hello @bjorns163,

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[mattermost-build]

This PR has been automatically labelled "stale" because it hasn't had recent activity.
A core team member will check in on the status of the PR to help with questions.
Thank you for your contribution!

[bjorns163]

/check-cla