cherry-pick: Correct theme value for Snap UI footer buttons (#29495)

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## **Description**

Cherry-pick
1fbb63c
to the RC.

The Snap UI footer buttons use the DS button which forces light theme,
this does not work for the colors used in the Snap buttons, therefore we
revert back to using the actually selected theme.

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ui/components/app/snaps/snap-ui-footer-button/snap-ui-footer-button.tsx

@@ -84,6 +84,7 @@ export const SnapUIFooterButton: FunctionComponent<
         alignItems: AlignItems.center,
         flexDirection: FlexDirection.Row,
       }}
+      data-theme={null}
     >
       {isSnapAction && !hideSnapBranding && (
         <SnapIcon snapId={snapId} avatarSize={IconSize.Sm} marginRight={2} />