Fix alias id when drop all aggregates

[dnhatn]

When dropping all aggregates, we create a synthetic aggregate referring to the first grouping. However, we use the ID of the first aggregate instead of the first grouping, which can lead to a single attribute referring to multiple channels when building the layout.

java.lang.AssertionError: Duplicate name ids are not allowed in layouts
    at org.elasticsearch.xpack.esql.planner.Layout$Builder.build(Layout.java:118) ~[?:?]
    at org.elasticsearch.xpack.esql.planner.AbstractPhysicalOperationProviders.groupingPhysicalOperation(AbstractPhysicalOperationProviders.java:190) ~[?:?]

[elasticsearchmachine]

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

[bpintea]

Good find, thanks Nhat.

[elasticsearchmachine]

Hi @dnhatn, I've created a changelog YAML for you.

[dnhatn]

Thanks @bpintea!

[elasticsearchmachine]

💔 Backport failed

Status	Branch	Result
❌	8.19	Commit could not be cherrypicked due to conflicts
❌	9.1	Commit could not be cherrypicked due to conflicts
❌	9.0	Commit could not be cherrypicked due to conflicts

You can use sqren/backport to manually backport by running backport --upstream elastic/elasticsearch --pr 135247