Fix unexpected output failure in test_bug025

test_bug025 was added to show a problem with a user reported error in WT-7208. The test removes an index file when the connection is closed, then reopens the connection. It appears that a "No such file or directory" was reported as a side effect of RTS, but RTS was recently changed to not give a message. We should make the test case resilient against any messages, as the messages are not really the point of the test.