Add workers.celery.env & workers.kubernetes.env

[Miretpl]

closes: #28880

This PR introduces two new fields: workers.celery.env and workers.kubernetes.env. The workers.env field is now deprecated.

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[Miretpl]

@jscheffl this is the last one, so we can close #28880 after it I think. Huge thanks for all the reviews and merges - for sure, without them, we wouldn't have finished it so quickly

[jscheffl]

Wow. This was a stretch!

[github-actions]

Backport successfully created: chart/v1-2x-test

Note: As of Merging PRs targeted for Airflow 3.X
the committer who merges the PR is responsible for backporting the PRs that are bug fixes (generally speaking) to the maintenance branches.

In matter of doubt please ask in #release-management Slack channel.

Status	Branch	Result
✅	chart/v1-2x-test