[TASK] Remove old JS in page header

Change-Id: I509ffe2cc3dc37cc08de3633c79127c1f50145a7
Resolves: #45528
Releases: 6.1
Reviewed-on: https://review.typo3.org/18313
Reviewed-by: Oliver Klee
Reviewed-by: Dmitry Dulepov
Tested-by: Dmitry Dulepov
Reviewed-by: Markus Klein
Reviewed-by: Henrik Ziegenhain
Reviewed-by: Thomas Loeffler
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring
Reviewed-by: Wouter Wolters
Reviewed-by: Benjamin Mack
Tested-by: Benjamin Mack