MDEV-36461: Optimizer trace: remove join_execution node

In non-EXPLAIN queries with subqueries, the trace was flooded
with empty "join_execution":{} nodes. Now, they are gone.

The "Range checked for each record" optimization still prints
content into trace on join execution. Now, we wrap it into
"range-checked-for-each-record" to delimit the invocations.
This new object has fields "select_id" which corresponds to
the outer query block, and the "loop" which corresponds to
the  inner query block iteration number. Additionally,
the field  "row_estimation" which itself is an object has
"table", and "range_analysis" fields that were moved
from the old "join_execution"'s steps array.

Author: bsrikanth-mariadb