ESQL Push down optimizations

[wchaparro]

Description

This is a list of push down optimizations we know we can make that should improve performance.

[elasticsearchmachine]

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

[nik9000]

Specifically we're looking to push filters to lucene.

• ESQL: Push queries on meta attributes to lucene #127609
• ESQL: pushdown to_upper/to_lower in like/rlike #127479
• Avoid pushing TopN of runtime Fields to Lucene #118043
• TO_LOWER(text_field) == "foo" ESQL: Rewrite TO_UPPER/TO_LOWER comparisons #118870
• TO_LOWER(text_field) != "foo" ESQL: Rewrite TO_UPPER/TO_LOWER comparisons #118870