[DOCS][8.19] Promote ESQL search functions to GA in the docs (#129897)

Promote ESQL search functions to GA in the docs

- removed `preview = true` from java function annotations for full-text search functions
- generated updates to asciidoc and kibana docs
- 8.x equivalent of #129786

Author: leemthompo

docs/reference/esql/esql-limitations.asciidoc

@@ -106,8 +106,7 @@ is currently experimental.
 [[esql-limitations-full-text-search]]
 === Full-text search
 
-experimental:[] {esql}'s support for <<esql-search-functions,full-text search>>
-is currently in Technical Preview. One limitation of full-text search is that
+One limitation of <<esql-search-functions,full-text search>> is that
 it is necessary to use the search function, like <<esql-match>>, in a <<esql-where>> command
 directly after the <<esql-from>> source command, or close enough to it.
 Otherwise, the query will fail with a validation error.