Add removal_resume_export to zts-report.py

Add the removal_resume_export test case to the possible failure
section of the zts-report.py and reference the Github issue.  In
the CI environment this test has proven to be unreliable due to
the way it detects the removal thread.  This is a flaw in the test
and not device removal so update the result summary accordingly.

Additionally, increase the allowed timeout in an effort to reduce
the observed rate of false positves.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #7895
Issue #7894

tests/test-runner/bin/zts-report.py

@@ -256,6 +256,7 @@ maybe = {
     'no_space/enospc_002_pos': ['FAIL', enospc_reason],
     'projectquota/setup': ['SKIP', exec_reason],
     'redundancy/redundancy_004_neg': ['FAIL', '7290'],
+    'removal/removal_resume_export': ['FAIL', '7894'],
     'reservation/reservation_008_pos': ['FAIL', '7741'],
     'reservation/reservation_018_pos': ['FAIL', '5642'],
     'rsend/rsend_019_pos': ['FAIL', '6086'],