feat: refactor Info Label

[InnaAtanasova]

Related Issue

Part of #1238

Description

This PR fixes one of the issues reported during Defect Hunting regarding Info Label with Icon missing border.

• SCSS variables that were used only once in the code have been removed
• The fd-info-label--only-icon class has been removed.

Screenshots

Before:

After:

Please check whether the PR fulfills the following requirements

• all items on the PR Review Checklist are addressed :
  https://github.com/SAP/fundamental-styles/wiki/PR-Review-Checklist

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[salarenko]

• There is a difference in font size depending whether the icon has been used
  

• Why did you removed --icon-only class? I remember Info Label had to use some specific padding if used only with an icon.

[InnaAtanasova]

• Why did you removed --icon-only class? I remember Info Label had to use some specific padding if used only with an icon.

The "default" padding is padding: 0 0.625rem;
These are the paddings when you have Text + Icon and Icon Only:

It's clear that in both cases they are the same. I don't see the need of having an additional class doing nothing :)

[InnaAtanasova]

• There is a difference in font size depending whether the icon has been used
  

@salarenko I fixed this