Slider gets wrong initial value with fractional range

### Tested versions

4.3dev4

### System information

Ubuntu 23.04 23.04 - X11 - Vulkan (Forward+)

### Issue description

With some combination of min/max/step/value of a slider, the actual retrieved initial value from GDScript is not equal to the value set in the editor.

### Steps to reproduce

The below table lists some combinations of the properties. All other properties remain in default except for `step=0.1` for all experiments. It shows that for some combinations the actual value isn't what is expected.

min | max | value | actual initial value
---- | ---- | ---- | ---- |
0 | 100 | 0 | 0
0 | 1 | 0 | 0
0 | 0.5 | 0 | 0
-1 | 1 | 0 | 0
-0.9 | 1 | 0 | 0.1
-1.1 | 1 | 0 | -0.1
-1.4 | 1 | 0 | -0.4
-1.7 | 1 | 0 | 0.3
-1.7 | 5 | 0 | 0.3
-1.7 | 0 | 0 | 0

For what I have seen so far at least the following pattern always goes wrong:
`step` = 0.1, `value` = 0 (default), `min value` < 0 and is fractional, `max value` > 0

One case that causes error.

How it looks like in the editor (value = 0) and how it looks like in runtime (value = 0.5)

The issue seems disappear if I explicitly set `value` to something that is not the default 0 in the editor, but this is not a workaround if I truly want the initial value to be 0.

### Minimal reproduction project (MRP)

[slider_bug.zip](https://github.com/godotengine/godot/files/14526658/slider_bug.zip)

I found that after opening the project, the `value` property is automatically set to 0.5 even though the packed scene does not say that. Reset it to 0 and run the scene and one can see that the value is still 0.5.

Start with the attached minimal reproduction project and reproduce the Slider property combinations using step=0.1, especially fractional negative min values with value=0. Compare the editor's value with the runtime value; done means the initial runtime value matches the value saved in the editor, including 0.

Written by the indexing model from the issue text.