Change default user id and gid

[lfrancke]

Description

Part of stackabletech/issues#645

Important

This should only be merged after the 24.11 release so it'll only make it into 25.3

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 its own securityContext.runAsUser or runAsGroup.

As of now all our operators do set these (and fsGroup) to 1000 and 0 respectively.
As the next step we want to remove that hardcoding so the default would then fall back to what we specify here.

Therefore I do believe that this PR should be a simple change with no downstream consequences.

Definition of Done Checklist

Tasks

Beta Give feedback

1. Changes are OpenShift compatible
2. Add an entry to the CHANGELOG.md file
3. 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>.

[stackable-bot]

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