[BUGFIX] Workspace grid remains empty due to AJAX timeout

With a large amount of unpublished changes, the workspace grid requires
a longer Ajax timeout than the default 30s (similar to the mass
actions).

Resolves: #54922
Releases: master, 6.2
Change-Id: I7e81e1f7ce989599c9fc17a6e698a31a79e474d5
Reviewed-on: http://review.typo3.org/26767


Reviewed-by: Benjamin Mack <benni@typo3.org>
Tested-by: Benjamin Mack <benni@typo3.org>
Reviewed-by: Frank Nägler <frank.naegler@typo3.org>
Tested-by: Frank Nägler <frank.naegler@typo3.org>