chore(e2e): rewrite e2e config init

[slonka]

Motivation

That way in a parent project we can get the default and overwrite only the parts of the config that we care about. So if a change happens like in https://github.com/kumahq/kuma/pull/12982/files#diff-4097df65e73d6b3a2813df0ea3c87f15a6c43ba3aca9b73b3e60346758ef0344R65 we won't need to modify the parent project.

Instead of #13163 we can just manually init the e2e config and in parent project use init to change the Config.

First review parent project.

Implementation information

Manually init the e2e configuration by moving the init function to RunE2ESpecs.

[github-actions]

Reviewer Checklist

🔍 Each of these sections need to be checked by the reviewer of the PR 🔍:
If something doesn't apply please check the box and add a justification if the reason is non obvious.

• Is the PR title satisfactory? Is this part of a larger feature and should be grouped using > Changelog?
• PR description is clear and complete. It Links to relevant issue as well as docs and UI issues
• This will not break child repos: it doesn't hardcode values (.e.g "kumahq" as an image registry)
• IPv6 is taken into account (.e.g: no string concatenation of host port)
• Tests (Unit test, E2E tests, manual test on universal and k8s)
  • Don't forget ci/ labels to run additional/fewer tests
• Does this contain a change that needs to be notified to users? In this case, UPGRADE.md should be updated.
• Does it need to be backported according to the backporting policy? (this GH action will add "backport" label based on these file globs, if you want to prevent it from adding the "backport" label use no-backport-autolabel label)