tests: make test-delay-split-region stable (#7210)
tests: make test-delay-split-region stable (#7210)

Signed-off-by: Jay Lee <2b53900d99d9dec83fb079f280f37f8f23b61cc6@gmail.com>
BusyJay/tikv,BusyJay/tikv,c4pt0r/tikv,pingcap/tikv,BusyJay/tikv,BusyJay/tikv,pingcap/tikv