[TASK] Remove duplicated code from typo3-backend-icon component

The `typo3-backend-icon` component code contains a duplicated
code fragment. This patch removes one occurrence.

Resolves: #104199
Releases: main, 12.4
Change-Id: I0530f89f646c5c2fda8a170f3792a28a2c04243d
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/84840


Tested-by: core-ci <typo3@b13.com>
Tested-by: Andreas Kienast <a.fernandez@scripting-base.de>
Reviewed-by: Andreas Kienast <a.fernandez@scripting-base.de>

Build/Sources/TypeScript/backend/element/icon-element.ts

@@ -84,9 +84,3 @@ declare global {
     'typo3-backend-icon': IconElement;
   }
 }
-
-declare global {
-  interface HTMLElementTagNameMap {
-    'typo3-backend-icon': IconElement;
-  }
-}