[Editor] Remove redundant code from EditorSpinSlider

[AThousandShips]

While working on some other code I ran into some issues with the range when using up/down with the inspector, the underlying range already does clamping, which is configurable with greater/less, so all this code does is ignore those flags, otherwise the code is redundant

This makes the behavior of the spin up/down consistent with the key input (which is especially relevant for float exports as they don't show the up/down)

Also moved some of the code into the cases where it's used, and cleaned up some minor details

Tested and confirmed the code without clamping works correctly, not reintroducing the issues described in:

• EditorSpinSlider: Change input via ´down´ or ´up´ arrow key #81272

[KoBeWi]

This makes the behavior of the spin up/down consistent with the key input (which is especially relevant for float exports as they don't show the up/down)

Doesn't seem like inspector EditorSpinSliders property handle key input.

How this can be tested?

[AThousandShips]

Doesn't seem like inspector EditorSpinSliders property handle key input.

How do you mean? Select the text input and use the up/down keys

[AThousandShips]

To illustrate how this is extra confusing and nasty:

• Create a script exporting a float, just plain export, no range needed (the default configuration is equivalent to "-99999,99999,1,or_greater,or_less,hide_slider")
• Enter 200000 into the property
• Select the property and push the arrow up key

It will jump back to 99999, the default upper range value, the fact you can't go from 99999 to 100000 alone is a bit annoying, but that side was what made me really confused when I was working on another PR, and what made me investigate this code

[akien-mga]

Thanks!

[AThousandShips]

Thank you!