Query.Lock(boolean) ignores false

### Task List

- [x] Steps to reproduce provided
- [ ] Stacktrace (if present) provided
- [ ] Example that reproduces the problem uploaded to Github
- [x] Full description of the issue provided (see below)

### Steps to Reproduce
1. Call `Query.lock(false)`
3. Observe that it still locks

### Expected Behaviour
If false is passed into the method it should set `LockModeType.NONE`.

### Actual Behaviour
`LockModeType.PESSIMISTIC_WRITE` is always used.

### Example Application
This is easy to verify by inspecting the short method:
https://github.com/grails/grails-data-mapping/blob/ef1730a42bc515cfb96cf9175d81e344d8a08a61/grails-datastore-core/src/main/groovy/org/grails/datastore/mapping/query/Query.java#L137-L140

Start with grails-datastore-core/src/main/groovy/org/grails/datastore/mapping/query/Query.java at the linked lines for Query.lock(boolean). Verify the method's behavior for both true and false inputs; done means false selects LockModeType.NONE while preserving the existing locking behavior for true.

Written by the indexing model from the issue text.