[BUGFIX] "Add media by URL" is not hidden if maxItems is reached

The "Add media by URL" button for FAL realtions is not hidden
if maxItems has already been reached by the opened record.

Change-Id: I71a27cbabd1fc6660f58d0374595af0558fb8a12
Resolves: #72408
Related: #70762
Releases: master, 7.6
Reviewed-on: https://review.typo3.org/45419


Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Tested-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>