Inconsistent enum strings in hover window of Initial Position Type

### Tested versions

- Reproducible in: 4.6.3.stable, 4.7.stable

### System information

N/A

### Issue description

All enum strings (other then "Absolute") begin with "Center of", but hovering shows:
- 1 - "Primary Screen Center"
- 3 - "Other Screen Center"

They should probably be set to the enum value itself, to avoid these inconsistencies in the future.

### Steps to reproduce

- Project Settings > General > Display > Window > Size
- Hover over Initial Position Type and compare it with its drop down menu

### Minimal reproduction project (MRP)

N/A

Reproduce the issue at Project Settings > General > Display > Window > Size by hovering over Initial Position Type and comparing the tooltip with the dropdown entries. Find the setting's enum string definitions, make the hover text match the enum values, and verify that all entries are consistent.

Written by the indexing model from the issue text.