This patch overrides the antlr3 function that allocates the missing
tokens that would eventually leak. The override stores these tokens in
a vector, ensuring memory is freed whenever the parser is destroyed.
Solution is copied from CQL implementation.
A unit test to reproduce the issue is added - leak would be reported
by ASAN, when running this test in debug mode - the test passed but
the leak is discovered when the test file exits.
Fixes#25878Closesscylladb/scylladb#25930
776f90e2f8