Getting DocumentLockedException instead of TimeoutException in FIT LockTest

The Python SDK is using error context fields to return a more specific exception type. In this case, if the "key_value_locked" retry reason is present in the context, the SDK returns DocumentLockedException instead of TimeoutException. 

We might only need a drive-side change to handle the Python SDK's behaviour unless this is something we can and want to change.

Failing Tests:

• LockTest.getAndLockTimeoutHasRetryReasonLocked
• LockTest.upsertLockedDocumentTimeoutHasRetryReasonLocked
• LockTest.verifyGetAndLockDoubleLock
• TouchTest.verifyTouchingLocked