Here's a second patch that makes BlobClob4BlobTest and DeadlockModeTest use the reduced timeouts when running against encrypted databases. The patch changes the order of the decorators so that the DatabasePropertyTestSetup executes inside the encryption decorator, and this ensures that it works on the encrypted database instead of on the default database.
DeadlockModeTest had one more problem that needed to be fixed. The encrypted variant always worked on the default (non-encrypted) database, not only when setting the timeouts, but also when doing database operations in the test case. The reason for this was that all the database connections were opened in helper threads, and the decorators only change the test configuration for the current thread (in a thread local field in TestConfiguration), so the connections would always be opened against the default database. I therefore made the test open all the connections in the main JUnit thread and pass the Connection objects as arguments to the helper threads when creating them.
With this patch, the time to run BlobClob4BlobTest was reduced from 5 min 25 sec to 1 min 40 sec in my environment. (No change in run time for DeadlockModeTest since it doesn't usually see lock timeouts.)