ZTS: redundancy_draid_spare{1,3} exceptions

Update the redundancy_draid_spare1 exception to reference an issue
which describes the failure.

Remove the exception for the redundancy_draid_spare3 test.  I have
not observed it in local testing.  If it reproduces in the CI we
can create a new issue for it and put back the exception.

Signed-off-by: Brian Behlendorf <[email protected]>

Author: behlendorf

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

@@ -254,8 +254,7 @@ maybe = {
     'projectquota/setup': ['SKIP', exec_reason],
     'raidz/raidz_002_pos': ['FAIL', known_reason],
     'raidz/raidz_expand_001_pos': ['FAIL', 16421],
-    'redundancy/redundancy_draid_spare1': ['FAIL', known_reason],
-    'redundancy/redundancy_draid_spare3': ['FAIL', known_reason],
+    'redundancy/redundancy_draid_spare1': ['FAIL', 18307],
     'removal/removal_condense_export': ['FAIL', known_reason],
     'renameat2/setup': ['SKIP', renameat2_reason],
     'reservation/reservation_008_pos': ['FAIL', 7741],