[ML] Increase Test Coverage 7.15

[walterra]

Follow up to #97982.

Meta issue to summarize improvements to test coverage for 7.15.

Jest unit tests

APM Correlations

• Test empty chart state (WR)
  [ML] APM Latency Correlations: Fix empty state #109813
• Time unit formatting (WR)
  [ML] APM Latency Correlations: Fix formatting of duration values for log x axis and selection badge. #109214
• asyncSearchServiceLogProvider(), asyncSearchServiceStateProvider(), getPrioritizedFieldValuePairs(), getRequestBase(), fetchTransactionDurationHistograms(), hasPrefixToInclude() (WR)
  [ML] APM Latency Correlations: Field/value candidates prioritization #107370

API integration tests

part of #63700

• /api/ml/job_audit_messages (DA) [ML] Add job audit messages API integration tests #110793
• /api/ml/jobs/force_start_datafeeds (PH) [ML] Add API integration tests for start and stop datafeeds #110961
• /api/ml/jobs/stop_datafeeds (PH) [ML] Add API integration tests for start and stop datafeeds #110961

APM Correlations

• trace_samples (WR)
  [ML] Move APM Latency Correlations from flyout to transactions page. #107266
• apmFailedTransactionsCorrelationsSearchStrategy (QN)
  [ML] Fix UI inconsistencies in APM Failed transaction correlations #109187

Functional tests

• Transform user permissions (PH)
  [ML] Transforms: Add functional tests for UI permissions #106693
• Import / Export jobs UI (JG) [ML] Job import and export functional tests #110578
• Jobs in stack management (including manage spaces) (RO)
  • [ML] Functional tests - add UI tests for stack management jobs sync #108402
  • [ML] Functional tests - add UI tests for jobs spaces management #109431
• Delayed data (MA)
  [ML] Anomaly detection: Adds functional test for delayed data chart flyout #109026

APM Correlations

• Transaction details page latency correlations tab (WR)
  [ML] Move APM Latency Correlations from flyout to transactions page. #107266
• Failed transaction correlations (QN)
  [ML] Fix UI inconsistencies in APM Failed transaction correlations #109187

Accessibility tests

part of #88496

[elasticmachine]

Pinging @elastic/ml-ui (:ml)

[peteharverson]

Closing issue as all the items have now been addressed for 7.15.0.