[TASK] Remove dummy files from ext:rtehtmlarea

Change-Id: Idb2fe1df112c3794e6852f270f742cfe51b2c480
Resolves: #47799
Related: #47756
Releases: 6.2
Reviewed-on: https://review.typo3.org/20390
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn