[CLEANUP] Replace wrong/old file copyright comments

All files should have the same file comment with the
same copyright notice in it. Also there must not be
an author any more. Instead the Extbase Team is
mentioned as author from now on.

Releases: 6.1
Fixes: #43883
Change-Id: Ib61859a2fa853a238907df314f948da51306d7e8
Reviewed-on: https://review.typo3.org/17099
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring