[TASK] impexp: Remove "Max file size" restriction

The export modules has a file size restriction
that skips file exports if they are bigger than
by default 1MB. This can be raised with an input
field.
The patch removes that input field:
* Configured maximum file sizes are checked during
  upload already. A well configured system should
  expect existing files are ok and just export everything
* The 1MB default size is old fashioned. Typical images
  are often bigger in size and resized only during FE
  rendering
* Skipping arbitrary files in export has a negative
  impact on data consistency of the export.
* Single files can still be excluded from export if
  needed
* Users up until now usually had manually raised the
  limit to some value high enough to make all files fit

Change-Id: Ib70dc48de44d215067474b4c3f6fff8988ab7712
Resolves: #83596
Releases: master
Reviewed-on: https://review.typo3.org/55382


Reviewed-by: Reiner Teubner <rteubner@me.com>
Tested-by: TYPO3com <no-reply@typo3.com>
Tested-by: Reiner Teubner <rteubner@me.com>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>