MDEV-10779 Failing assertion lex->proc_list.elements == 0 or syntax error on PROCEDURE ANALYSE in UNION

Reverting a part of the patch for "MDEV-8909union parser cleanup",
as a parenthesized SELECT with PROCEDURE followed by UNION is not
disallowed by the grammar (only a non-parenthesized SELECT with PROCEDURE
followed by a UNION is disallowed grammatically).