[CLEANUP] Remove comment header in ext_emconf

The "do not touch me" comment header in ext_emconf.php files
of system extensions are misleading since we are editing those
files manually for years now. Remove those headers.

Change-Id: I27f6253effa54dae7f92170175e7705cc706d03a
Resolves: #60129
Releases: 6.3, 6.2
Reviewed-on: https://review.typo3.org/31405
Reviewed-by: Jigal van Hemert
Tested-by: Jigal van Hemert