MDEV-34720: Poor plan choice for large JOIN with ORDER BY and small LIMIT

(Variant 2b: call greedy_search() twice, correct handling for limited
 search_depth)

Modify the join optimizer to specifically try to produce join orders that
can short-cut their execution for ORDER BY..LIMIT clause.

The optimization is controlled by @@optimizer_join_limit_pref_ratio.
Default value 0 means don't construct short-cutting join orders.
Other value means construct short-cutting join order, and prefer it only
if it promises speedup of more than #value times.

In Optimizer Trace, look for these names:
* join_limit_shortcut_is_applicable
* join_limit_shortcut_plan_search
* join_limit_shortcut_choice

Author: spetrunia

mysql-test/main/mysqld--help.result

@@ -724,6 +724,15 @@ The following specify which files/extra groups are read (specified before remain
  keys. This variable will be deleted in MariaDB 11.0 as it
  is not needed with the new 11.0 optimizer.
  Use 'ALL' to set all combinations.
+ --optimizer-join-limit-pref-ratio=# 
+ For queries with JOIN and ORDER BY LIMIT : make the
+ optimizer consider a join order that allows to short-cut
+ execution after producing #LIMIT matches if that promises
+ N times speedup. (A conservative setting here would be is
+ a high value, like 100 so the short-cutting plan is used
+ if it promises a speedup of 100x or more). Short-cutting
+ plans are inherently risky so the default is 0 which
+ means do not consider this optimization
  --optimizer-max-sel-arg-weight=# 
  The maximum weight of the SEL_ARG graph. Set to 0 for no
  limit
@@ -1697,6 +1706,7 @@ old-mode UTF8_IS_UTF8MB3
 old-passwords FALSE
 old-style-user-limits FALSE
 optimizer-adjust-secondary-key-costs 
+optimizer-join-limit-pref-ratio 0
 optimizer-max-sel-arg-weight 32000
 optimizer-max-sel-args 16000
 optimizer-prune-level 1