Not creating explicit record locks will speed up the test.
Also, disable the use of InnoDB persistent statistics in the test of
MDEV-27270 to avoid intermittent failures in 10.6 or later
(after commit 9608773f75)
due to the nondeterministic scheduling of STATS_AUTO_PERSISTENT.
In main.index_merge_myisam we remove the test that was added in
commit a2d24def8c because
it duplicates the test case that was added in
commit 5af12e4635.
For a key with keyparts (k1,k2,k3) , if we are building a range over the keyparts
we should make sure that if min_value/max_value for a keypart is not added to
key buffer then the keyparts following should also not be allowed.
