[APM] Latency correlations 7.16 meta issue

[walterra]

Meta issue detailing improvements for 7.16 to the Latency correlations feature added in 7.14 in #99905.
Follow up to 7.15 #106381.

Must have

Should have

• Display alternate values - If AMEX is correlated, what other values exist as payment method. Correlated terms visuals - more context for terms identified as correlated. e.g. What other payment type values exist? Could likely reuse some of the data viz charts.
  [APM] Correlations: Show additional context per field (indicate top 5 values) #95272
• Top level visual for failed transactions would balance the page. As quick-win, suggest trial re-using latency chart, with counts of failure/success transactions.
  [ML] APM Correlations: Chart for failed transactions correlations tab. #110172
• Add info on latency chart to help popover for failed transactions correlations chart
  [ML] APM Correlations: Chart for failed transactions correlations tab. #110172 (comment)
• Make row selection more "sticky" - the chart updates on hover, but if the table looses focus then the top row is displayed. This makes it hard to interact with the chart for any term other than the top one.
  [APM] Correlations: Allow users to focus on one of the items in the table #93907
• View in expert mode shows extra columns for failed txn correlations, persistent setting for user browser
  [ML] Display advanced mode toggle for the APM failed transactions table #114363
• Platinum License check on search strategy API level, fixed as part of [ML] APM Correlations: Fix usage in load balancing/HA setups. #115145
• Fix Correlation analysis in load balancing/HA setups
  [APM] Latency distribution chart fails to load with AsyncSearchService error #114046

Could have

Backlog

Tech Debt

• delete no longer needed significant terms based API endpoints
  [ML] APM Correlations: Remove unused code. #112645
• delete no longer needed code in server/lib/correlations/latency
  [ML] APM Correlations: Remove unused server side queries code. #113263
• Revisit the generator based function fetchTransactionDurationHistograms and replace id with promises (preferably) or observables since that's what we already use and we should keep the number of async concepts down when possible.
  [ML] Fix UI inconsistencies in APM Failed transaction correlations #109187 (comment)
• Consolidate code that we worked on in parallel for trace samples / latency correlations / failed transactions
  [ML] APM Latency Correlations: Code consolidation. #110790

Research

[elasticmachine]

Pinging @elastic/ml-ui (:ml)

[elasticmachine]

Pinging @elastic/apm-ui (Team:apm)

[peteharverson]

Closing issue as all items planned for 7.16 have been completed.