[TASK] Increase cache db backend blob

Sets the typo3 database cache backend "content" field
from mediumblob to longblob.
Mediumblob on mysql equals 16MB max storage, which can
be too small for cache entries. Switching to longblob
increases single cache row size to 4GB and costs only
one additional byte per row.

Change-Id: I1ab5b84b6845280e77e339cbe4a59e0043f84cc2
Resolves: #83772
Releases: master
Reviewed-on: https://review.typo3.org/55549


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Tested-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>