SpinDensity's low memory mode is inaccessible from the application level.

**Describe the bug**
Currently EstimatorManagerNew uses a constructor that does not correctly set data_locality based on the save_memory input. Input Testing doesn't protect this input. Also no integration testing is tripped if the correct constructor is changed. Unit testing covers the functionality but doesn't require input with this set.

**To Reproduce**
Steps to reproduce the behavior:
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You would expect now there to be only one grid allocated per rank, there will still be one per crowd.

**Expected behavior**
The implemented feature to work.

**System:**
This is by inspection so I could be wrong but the test coverage is still insufficient because #6184 removed the input completely and no testing broke.

**Additional context**
Add any other context about the problem here.