[CLEANUP] Remove unused JS for pinging loginrefreshed

There are still some leftover calls to save information
when the page was loaded at the latest. The whole
top.busy object does not exist in the core anymore
and can safely be removed.

Resolves: #62795
Releases: master
Change-Id: Ic5475470b86182bd8f6f4af05c05d8fa9e571f3f
Reviewed-on: http://review.typo3.org/33921
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>