This test was using a sleep of 1 second in an attempt to ensure that the
timestamp that is part of an InnoDB status string would increase.
This not only prolongs the test execution time by 1+1 seconds, but it
also is inaccurate. It is possible that the actual sleep duration is
less than a second.

Let us wait for the creation of the file ib_buffer_pool and then wait
for the buffer pool dump completion. In that way, the test can complete
in a dozen or two milliseconds (1% of the previous duration) and work
more reliably.