Fix: Always use the 24.7.0 version of the tools image because testing PR artifacts breaks otherwise

[dervoeti]

This fixes testing of PR versions of secret-operator since the testruns got broken by #476

We stumbed across this:

When I run a custom test with secret-operator I’m allowed to choose a PR-Version like secret=0.0.0-pr455 which then in the secret-migration Job causes the image being docker.stackable.tech/stackable/tools:1.0.0-stackable0.0.0-pr455 which is a consequence of the image selection mechanism.

Since the tools image does not have PR artifacts that relate to the PRs in secret-operator we now specify a fixed version so that testing PRs works again. Currently it fails because the according tools image is not present.
We're using 24.7.0 because it's multiarch. It's manually built for now to make this work and will get rebuilt by the release process later.

[Maleware]

LGTM,

the fix I needed, thank you! :)

We can merged it's checked by the release team and we gonna include it.