Allow to set default flakeguard runner

[lukaszcl]

Allow to change default flakeguard runner which is ubuntu-latest by default.

To do it call ./.github/workflows/flakeguard.yml workflow with default_tests_runner in extraArgs. E.g.

  trigger-flaky-test-detection-for-deployment-project:
    name: Flakeguard Deployment Project
    uses: ./.github/workflows/flakeguard.yml
    needs: [detect-changes]
    if: ${{ needs.detect-changes.outputs.deployment-changes == 'true'}}
    with:
      repoUrl: 'https://github.com/smartcontractkit/chainlink'
      projectPath: 'deployment'
      baseRef: ${{ github.base_ref }}
      headRef: ${{ github.head_ref }}
      maxPassRatio: '1.0'
      findByTestFilesDiff: true
      findByAffectedPackages: false
      slackNotificationAfterTestsChannelId: 'C07TRF65CNS' #flaky-test-detector-notifications
      extraArgs: '{ "skipped_tests": "TestAddLane", "run_with_race": "true", "print_failed_tests": "true", "test_repeat_count": "3", "omit_test_outputs_on_success": "true", "default_tests_runner": "<CUSTOM-RUNNER>" }'
    secrets:
      SLACK_BOT_TOKEN: ${{ secrets.QA_SLACK_API_KEY }}
      GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
      FLAKEGUARD_SPLUNK_ENDPOINT: ${{ secrets.FLAKEGUARD_SPLUNK_ENDPOINT }}
      FLAKEGUARD_SPLUNK_HEC: ${{ secrets.FLAKEGUARD_SPLUNK_HEC }}

[cl-sonarqube-production]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

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