Polish Reduce Red Eye UI

Summary:
The bottom toolbar of the {nav Reduce Red Eye} tool sports a couple of
glitches and inconsistencies:
- The vertical height is too large compared to the {nav Crop} tool.
- After {nav Size} the colon is missing.
- For some languages the slider can become quite long.
- After accepting, sometimes the left text flickers, since it is updated before the layout changes back.
- The {nav OK} button is missing a more descriptive text and more fitting icon as featured by the {nav Crop} tool.
- {nav Crop} uses the standard {nav Cancel} wording, but here a confusing {nav Close} button is placed next to {nav OK}.
- When proceeding to fix the second eye after clicking on {nav OK}, the {nav Close} button suddenly gains focus and thus turns blue, which was not the case for the first eye.
- When pressing {key Enter} without having clicked first, `invalid rect` is printed.

Let's fix all of those issues.

Test Plan:
Issues are gone, no functional or visual regressions when playing around
with the tool.

Before: {F6193619}
After: {F6193618}

Reviewers: #gwenview, muhlenpfordt

Reviewed By: #gwenview, muhlenpfordt

Subscribers: muhlenpfordt

Differential Revision: https://phabricator.kde.org/D14846