[tests] fix flakiness in TestTabletCopyEncryptedServers

The TabletCopyITest.TestTabletCopyEncryptedServers scenario deletes
a tablet, and then checks to see that the tablet data state is
TABLET_DATA_COPYING.  However, it's possible for the remote bootstrap
to complete so quickly that it's already TABLET_DATA_READY at the time
of sampling, so from time to time the test failed with

  src/kudu/integration-tests/tablet_copy-itest.cc:1014: Failure
  Failed
  Bad status: Timed out: Timed out after 30.002s waiting for correct tablet state: Illegal state: State TABLET_DATA_READY unexpected, expected TABLET_DATA_COPYING

This patch updates the assertion to allow both the COPYING and READY
tablet data states.

Without the patch, the test was about 7% flaky [1]. With the patch,
it's not flaky [2].

[1] http://dist-test.cloudera.org/job?job_id=aserbin.1660260668.94650
[2] http://dist-test.cloudera.org/job?job_id=aserbin.1660261249.109365

Change-Id: I22933cc9cb727711ee5fb45c811c2a759958fdfa
Reviewed-on: http://gerrit.cloudera.org:8080/18842
Tested-by: Alexey Serbin <alexey@apache.org>
Reviewed-by: Yingchun Lai <acelyc1112009@gmail.com>
Reviewed-by: Abhishek Chennaka <achennaka@cloudera.com>
Reviewed-by: Attila Bukor <abukor@apache.org>
1 file changed