Frozen indices are deprecated which makes all the [SQL features supporting frozen indices](https://www.elastic.co/guide/en/elasticsearch/reference/current/sql-index-frozen.html) obsolete.

This includes:

* `index_include_frozen` request parameter in the `_sql` endpoint
* `index.include.frozen` (J|O)DBC driver settings
* `SHOW TABLES INCLUDE FROZEN` queries and the `FROZEN INDEX` kind in the corresponding response
* The `FROZEN` modifier in `FROM` clauses (as in `SELECT * FROM FROZEN archive`)

`_search` raises a deprecation warning when frozen indices are being searched with `ignore_throttled=false`. SQL could do the same when the `index_include_frozen` request parameter is set or when the `FROZEN` keyword is used.

Relates to https://github.com/elastic/elasticsearch/issues/70192
x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/parser/CommandBuilder.java
}
        Debug.Type type = null;
        if (ctx.type != null) {
            if (ctx.type.getType() == SqlBaseLexer.ANALYZED) {
                type = Debug.Type.ANALYZED;
            } else {
                type = Debug.Type.OPTIMIZED;
            }
        }
        boolean graphViz = ctx.format != null && ctx.format.getType() == SqlBaseLexer.GRAPHVIZ;
        Debug.Format format = graphViz ? Debug.Format.GRAPHVIZ : Debug.Format.TEXT;
        return new Debug(source, plan(ctx.statement()), type, format);
    }
    @Override
    public Command visitExplain(ExplainContext ctx) {
        Source source = source(ctx);
        if (ctx.PLAN().size() > 1) {
            throw new ParsingException(source, "Explain TYPE should be specified at most once");
        }
        if (ctx.FORMAT().size() > 1) {
            throw new ParsingException(source, "Explain FORMAT should be specified at most once");
        }
        if (ctx.VERIFY().size() > 1) {
            throw new ParsingException(source, "Explain VERIFY should be specified at most once");
        }
        Explain.Type type = null;
        if (ctx.type != null) {
            type = switch (ctx.type.getType()) {
                case SqlBaseLexer.PARSED -> Explain.Type.PARSED;
                case SqlBaseLexer.ANALYZED -> Explain.Type.ANALYZED;