[BUG] App-tray: App overflow doesn't use custom padding if specified

[ryanabx]

Cosmic-applets version:

Specific applet that this is regarding (if applicable):

app-tray

Issue/Bug description:

When using a custom padding for applets in the panel, the overflow menu of the app tray specifically, doesn't use the specified padding

Steps to reproduce:

• Define a custom padding for applets in the panel
• Open enough apps for the app tray to trigger overflow
• Observe

Expected behavior:

App tray uses the padding that the panel has

Other notes:

Here's a picture: