Fix memory leak in pm_parse_process

pm_parse_process initializes the index_lookup_table but nothing seems to
use it after it has been allocated. However, pm_compile_scope_node will
overwrite the index_lookup_table and cause it to leak memory. This can
be seen during bootup with the following memory leaks reported by ASAN:

    #0 0x60dba31b7af3 in malloc
    #1 0x60dba32e0718 in rb_gc_impl_malloc gc/default/default.c:8287:5
    #2 0x60dba32c7aa7 in ruby_xmalloc_body gc.c:5373:12
    #3 0x60dba32c4a54 in ruby_xmalloc gc.c:5355:34
    #4 0x60dba3260314 in pm_index_lookup_table_init_heap prism_compile.h:89:29
    #5 0x60dba3209388 in pm_parse_process prism_compile.c:11366:5

Author: peterzhu2118

prism_compile.c

@@ -11362,12 +11362,6 @@ pm_parse_process(pm_parse_result_t *result, pm_node_t *node, VALUE *script_lines
     pm_intern_constants_ctx_t intern_ctx = { .constants = scope_node->constants, .encoding = scope_node->encoding, .index = 0 };
     pm_parser_constants_each(parser, pm_intern_constants_callback, &intern_ctx);
 
-    pm_constant_id_list_t *locals = &scope_node->locals;
-    pm_index_lookup_table_init_heap(&scope_node->index_lookup_table, (int) constants_size);
-    for (size_t index = 0; index < locals->size; index++) {
-        pm_index_lookup_table_insert(&scope_node->index_lookup_table, locals->ids[index], (int) index);
-    }
-
     // If we got here, this is a success and we can return Qnil to indicate that
     // no error should be raised.
     result->parsed = true;