Change UID & GID to 1000/0

[lfrancke]

Description

Caution

Merge after #1200 is resolved (so we don't consume runners until we need to build everything).

Reverting the previous change from PR #1164

Reason: I thought I had tested this and everything would work with FSGroup set.
But it turns out that some tools seem to write some data with a permission set that is only accessible by the user (e.g. NiFi journals) so this will require more work and that'll happen after 25.7

Definition of Done Checklist

Note

Not all of these items are applicable to all PRs, the author should update this template to only leave the boxes in that are relevant.

Please make sure all these things are done and tick the boxes

• Changes are OpenShift compatible
• All added packages (via microdnf or otherwise) have a comment on why they are added
• Things not downloaded from Red Hat repositories should be mirrored in the Stackable repository and downloaded from there
• All packages should have (if available) signatures/hashes verified
• Add an entry to the CHANGELOG.md file
• Integration tests ran successfully

TIP: Running integration tests with a new product image

The image can be built and uploaded to the kind cluster with the following commands:

bake --product <product> --image-version <stackable-image-version>
kind load docker-image <image-tagged-with-the-major-version> --name=<name-of-your-test-cluster>

See the output of bake to retrieve the image tag for <image-tagged-with-the-major-version>.

[lfrancke]

Before merging this I'd like to see if the OPA & NiFi (& possibly others) tests work again.