[TASK] Performance: Use cache_hash with "mixed" data

The cache-frontend is VariableFrontendCache that already uses
serialize() or (if available) igbinary_serialie() itself.
No need to additionally serialize data.

Change-Id: I8c3cfd2a279f8a38bc5c4d860329f2333f1304a5
Resolves: #52648
Releases: 6.2
Reviewed-on: https://review.typo3.org/24512
Reviewed-by: Philipp Gampe
Tested-by: Philipp Gampe
Reviewed-by: Stefan Neufeind
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn