The first patch for the bug was erroneous: it did not take into account
the fact that the modified function get_key_scans_params() was called in
different contexts. As a result the patch caused a regression bug MDEV-22191.
The patch for this bug introduced an extra parameter. Actually we can
do without this parameter and use the fourth parameter for the same
puropose - to differentiate between the calls of the function for range
access and for index merge access.

Also removed the call of get_key_scans_params() in the code of the function
merge_same_index_scans() as not needed.