Excessive icon spacing in the Scene Tree dock pushes node names out of view

### Tested versions

v4.7.beta3.official [860821708]

### System information

w11

### Issue description

FullHD monitor
As shown in this screenshot, and in my opinion (and perhaps that of other users if they support this report), the spacing between icons is excessive—two gaps are equivalent to the width of a full icon.
My issue is that I have to expand the dock just to read the node names, because the icons are too far apart from each other and push the text out of view.

**Solution:**

* Reduce the spacing between icons.
* Enable an option in the Editor Settings to let users customize this separation according to their preferences.

I personally prefer the first option.

### Steps to reproduce

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### Minimal reproduction project (MRP)

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Start by reproducing the layout in the Scene Tree dock using Godot 4.7.beta3 on a FullHD display, comparing icon spacing with node-name visibility. Inspect the editor's Scene Tree dock entry point; done means the spacing is reduced so node names remain readable without widening the dock, with any customization behavior matching the chosen solution.

Written by the indexing model from the issue text.