Support partial results in ES|QL

[dnhatn]

• Support partial results in each cluster: Support partial results in ES|QL #121942

• Support partial results across clusters: Support partial results in CCS in ES|QL #122708

• Return shard-level failures (currently only returning the is_partial flag) Report failures on partial results #124823 Include failures in partial response #124929

• Introduce esql.query.allow_partial_results setting: Introduce allow_partial_results setting in ES|QL #122890

• Defaults to true: Allow partial results by default in ES|QL #125060 Allow partial results by default in ES|QL - Take 2 #127351

• Add documentation

• Handle partial_results in the final reduction

• Return fatal/non-fatal errors in data node responses to enable retries (or one shard at the time?)

• Allow partial results during field-caps/resolution

• Limit the list of allowed exceptions to support partial results

[elasticsearchmachine]

Pinging @elastic/es-analytical-engine (Team:Analytics)

[bpintea]

Related: #111518