test: do not remove state directory on failure

The test log is in the state directory, and we want to keep it around
when a test fails.

Follow-up for: 256a835f1c

test/test-functions

@@ -3040,7 +3040,6 @@ _test_cleanup() {
         fi
         [[ -n "$TESTDIR" ]] && rm -vfr "$TESTDIR"
         [[ -n "$STATEFILE" ]] && rm -vf "$STATEFILE"
-        [[ -n "$STATEDIR" ]] && rm -vfr "$STATEDIR"
     ) || :
 }
 
@@ -3255,7 +3254,8 @@ do_test() {
                 fi
                 test_cleanup
                 if [ $ret -eq 0 ]; then
-                    rm "$TESTLOG"
+                    # $TESTLOG is in $STATEDIR, so clean it up only on success
+                    [[ -n "$STATEDIR" ]] && rm -vfr "$STATEDIR"
                     echo "[OK]"
                 else
                     echo "[FAILED]"