[ML] Increase Test Coverage 8.4.0

[peteharverson]

Follow up to #130648.

Meta issue to summarize improvements to test coverage for 8.4.0.

API integration tests

• [x] PUT /api/ml/anomaly_detectors/:jobId (job with datafeed) (JG) https://github.com/elastic/kibana/pull/134986
• [x] GET /api/ml/filters/_stats (PH) https://github.com/elastic/kibana/pull/135118
• [ ] POST /api/ml/jobs/jobs
• [ ] POST /api/ml/jobs/jobs_summary
• [x] GET /api/ml/management/list/:listType (JG) https://github.com/elastic/kibana/pull/134893
• [ ] GET /api/ml/modules/jobs_exist/:moduleId
• [ ] POST /api/ml/saved_objects/remove_job_from_current_space
• [x] POST /api/ml/validate/datafeed_preview (correct and incorrect time range) (JG) https://github.com/elastic/kibana/pull/134073
• [x] POST /internal/aiops/explain_log_rate_spikes(WR) https://github.com/elastic/kibana/pull/135058 https://github.com/elastic/kibana/pull/135431

Functional tests

• [x] Creating ML jobs from Lens (JG) https://github.com/elastic/kibana/pull/133899
• [x] Transforms - num_failure_retries advanced setting https://github.com/elastic/kibana/pull/135486
• [ ] Data visualizer random sampler config (QN)
• [ ] Data visualizer filters (pinned filters) (QN)
• [ ] DFA wizard with saved search filters
• [ ] Explain log rate spikes (WR/MA) https://github.com/elastic/kibana/pull/138387
• [ ] 3rd party models (DA)
  • [x] Import models (RO) https://github.com/elastic/kibana/pull/136010
  • [x] Expanded row content of imported models (RO) https://github.com/elastic/kibana/pull/136010
  • [x] List
  • [x] Start deployment (DA) https://github.com/elastic/kibana/pull/138242
  • [x] Stop deployment (DA) https://github.com/elastic/kibana/pull/138242
  • [x] Delete model (DA) https://github.com/elastic/kibana/pull/138425
  • [ ] Test model

[elasticmachine]

Pinging @elastic/ml-ui (:ml)