The text used to be centered around a point left of the slider line
with the assumption that it displays a number from 0-1 and "%"
With the ability to set the unit name, this assumption is no longer true,
and if setting a long name (like "Frames" in #110540) the text overlaps the slider line
By right aligning the text on the left side of the slider, this overlap cannot happen anymore.
| Before | After |
| - | - |
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Pull Request: https://projects.blender.org/blender/blender/pulls/110586