IconButton height changes when IsLoading toggles with classes="Small"

[turboyang-cn]

Description

When using an IconButton with classes="Small", the control's height becomes inconsistent depending on the value of IsLoading.

Steps to Reproduce

1. Create an IconButton with classes="Small".
2. Toggle the IsLoading property between True and False.
3. Observe the control height.

Actual Behavior
The height of the IconButton changes when switching between IsLoading="True" and IsLoading="False".

Expected Behavior
The height of the control should remain consistent regardless of whether IsLoading is True or False.

Additional Notes
This behavior can lead to layout shifts in UI, especially when the button is used within constrained or aligned layouts.

[rabbitism]

I got a feeling the loading icon is still too large for small button, but need to investigate where the padding comes from.