[!!!][TASK] Remove static file edit magic

Configuring RTE fields TCA in defaultExtras section with static_write
enabled the DataHandler to write content to specific sections of files
in a specific directory.

This feature is documented and existed for a long time, but is not used
in the wild. Searching for keywords just revealed a very outdated
demo page, the according core source and documentation. No extension
or real live use case was found and even a call for feedback on this
by Benni half a year ago got no answers.

The patch removes this feature without substitution and improves
DataHandler performance as a nice side effect.

Resolves: #63818
Resolves: #63668
Releases: master
Change-Id: I5532ba1565370baeb03ce074c8ab8036a0936d5b
Reviewed-on: http://review.typo3.org/35369
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Reviewed-by: Helmut Hummel <helmut.hummel@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Benjamin Mack <benni@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>