ci: run integration-test in serial and ordered

[nschad]

How to categorize this PR?

/kind regression

What this PR does / why we need it:

Workaround problem that we can't create simultaneous isolated networks.

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Breaking changes:

[nschad]

/retest

[nschad]

/retest

[breuerfelix]

haven't seen these tests being green for a long time now .. :D

/approve

[ske-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: breuerfelix

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[breuerfelix]

/lgtm

[ske-prow]

LGTM label has been added.

Details

Git tree hash: 4f36a2a39aaf8bc6bdb27de99cd2edeb0880bf64

[nschad]

/retest

[ske-prow]

@nschad: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-gardener-extension-provider-stackit-integration-tests	65cc987	link	true	/test pull-gardener-extension-provider-stackit-integration-tests

Full PR test history. Your PR dashboard. Command help for this repository.
Please help us cut down on flakes by linking this test failure to an open flake report or filing a new flake report if you can't find an existing one. Also see the gardener testing guideline for how to avoid and hunt flakes.

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