helium/ui/layout: remove margin after pinned in vertical layout

[Jasdeep-Dhillon]

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Tested on (check one or more):

• Windows
• macOS
• Linux

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Related to issue #1498 which mentioned to remove the extra margin after pinned tabs when using vertical layout. I have removed the check which used collapsed state to show the separator which resulted in extra margin after pinned tab.

Before:

After:

[greptile-apps]

_{Reviews (1): Last reviewed commit: "helium/ui/layout: remove margin after pi..." | Re-trigger Greptile}