Fix aberration factor not taken into account for milkyway texture

[henrysky]

Fix aberration factor not taken into account for milkyway texture.

Fixes #4099

Screenshots (if appropriate):

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• This change requires a documentation update
• Housekeeping

How Has This Been Tested?

Visually, go to Mercury and set aberration to x5.0 and then toggle on and off to check how the milkyway texture move compared to stars.

Test Configuration:

• Operating system: MacOS 15.2
• Graphics Card: Apple M3

Checklist:

• My code follows the code style of this project.
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (header file)
• I have updated the respective chapter in the Stellarium User Guide
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[github-actions]

Great PR! Please pay attention to the following items before merging:

Files matching src/**/*.cpp:

• Are possibly unused includes removed?

This is an automatically generated QA checklist based on modified files.

[alex-w]

Thanks!

[10110111]

Not sure if this is related, but I get the following warning since your huge change to support Gaia-enabled catalog.

/home/ruslan/src/stellarium/src/core/modules/SolarSystem.cpp: In member function ‘virtual QList<QSharedPointerNoDelete<StelObject> > SolarSystem::searchAround(const Vec3d&, double, const StelCore*) const’:
/home/ruslan/src/stellarium/src/core/modules/SolarSystem.cpp:2522:20: warning: unused variable ‘withAberration’ [-Wunused-variable]
 2522 |         const bool withAberration=core->getUseAberration();
      |                    ^~~~~~~~~~~~~~

[alex-w]

This variable isn't used anymore in these method, so, I removed it