Add OpenShift support to K8s integration tests

[swiatekm]

What does this PR do?

Adds the ability to run K8s integration tests on Openshift.

Why is it important?

We want to validate that agent works correctly on all supported Openshift versions. This involves adding some openshift-specific bits to the orchestration script for the tests, as well as some adjustments to the tests themselves.

This PR doesn't actually provision the Openshift clusters or run the tests. This will happen in a follow-up.

Checklist

• I have read and understood the pull request guidelines of this project.
• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
  - [ ] I have made corresponding changes to the documentation
  - [ ] I have made corresponding change to the default configuration files
  - [ ] I have added tests that prove my fix is effective or that my feature works
  - [ ] I have added an entry in ./changelog/fragments using the changelog tool
• I have added an integration test or an E2E test

How to test this PR locally

First, install crc. Then:

EXTERNAL=true SNAPSHOT=true PLATFORMS="linux/amd64" PACKAGES=docker DOCKER_VARIANTS=basic mage package
crc setup
crc start --disk-size 50
eval $(crc oc-env)
export ELASTICSEARCH_HOST=""
export ELASTICSEARCH_USERNAME="elastic"
export ELASTICSEARCH_PASSWORD=""
export KIBANA_HOST=""
export KIBANA_USERNAME="elastic"
export KIBANA_PASSWORD=""
K8S_VERSION=1.32 TARGET_ARCH=amd64 K8S_DISTRIBUTION=openshift DOCKER_VARIANTS=basic .buildkite/scripts/buildkite-k8s-integration-tests.sh

Related issues

• Relates https://github.com/elastic/ingest-dev/issues/5216

[mergify]

This pull request does not have a backport label. Could you fix it @swiatekm? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-./d./d is the label that automatically backports to the 8./d branch. /d is the digit
• backport-active-all is the label that automatically backports to all active branches.
• backport-active-8 is the label that automatically backports to all active minor branches for the 8 major.
• backport-active-9 is the label that automatically backports to all active minor branches for the 9 major.

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarQube

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 77b0cf8

cc @swiatekm