chore: Change default user id and gid

[lfrancke]

Description

Part of stackabletech/issues#645
Part of stackabletech/issues#651

Note

This was already applied once before and later reverted.
It was merged prematurely back then but now the immediate parent issue has been done and it should be good to go again

Change default user id and gid to the same ones we use in the operators themselves.
These are only the defaults that are used when a Pod does not specify their own securityContext.runAsUser or runAsGroup.

All of our operators have been changed to not set the user and group id anymore which means they'll fall back to the values from the image.

Definition of Done Checklist

• Changes are OpenShift compatible
• 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>.