[BUGFIX] Wrong charset for DB fields cause problems

When DB fields whose intent is to store serialized data are set to
a wrong charset (i.e. latin1_swedish_ci instead of utf8) some
indexing entries cause problems.

Change-Id: I6564cc759818e72508ca606e246f1c099d2efbc4
Resolves: #55693
Releases: 3.0.0
Reviewed-on: https://review.typo3.org/27356
Reviewed-by: Ingo Renner
Tested-by: Ingo Renner