SQL: do not accept FROZEN queries

[costin]

Description

As frozen indices are deprecated and about to be removed, we should follow suite and remove said functionality from SQL.

1. queries using FROZEN should fail with an error that the functionality is not longer available
2. schedule the keyword removal down the line to simplify the grammar

Related to #120539, elastic/elasticsearch-sql-odbc#333

[elasticsearchmachine]

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