Tab icon configuration: settings not surviving restart when using classic theme

[thomasritter]

Currently, I am performing manual tests for https://github.com/eclipse-platform/eclipse.platform.ui/pull/1071

@shubhamWaghmare-sap & @praveen-skp please have a look at this.

The issue is that the settings do not survive a Eclipse restart if the classic theme is being selected.

Steps to reproduce

From a fresh installation of the latest iBuild and clean workspace:

• Open preference
• Go to appearance settings page
• Switch theme to classic
• Switch on new settings "Always show full titles" + "Hide icons"
• Press apply

I expected: Settings gets applied

But got: Tab icons still visible and titles not fully shown

A variation:

• Open preference
• Go to appearance settings page
• Switch on new settings "Always show full titles" + "Hide icons" while using the light theme
• Press apply
• Settings get applied and everything looks good. Tab icons not visible.
• Switch to classic theme -> Everything still good
• Restart Eclipse

I expected: Nothing changes

But got: Tab icons visible again and titles not fully shown

Tested under this environment:

• OS & version: MacOS Sonoma
• Eclipse IDE/Platform version (as shown in Help > About): I20240131-1800