[BUGFIX] be_users:usergroup_cached_list to small

The field usergroup_cached_list in be_users table
is to small. Make it a text field.

Change-Id: I45afa0880da20323329694073777a51dcfc2db4d
Resolves: #49962
Releases: 6.2
Reviewed-on: https://review.typo3.org/22284
Reviewed-by: Markus Klein
Tested-by: Markus Klein
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn