[BUGFIX] TS is fetched from cache incorrectly sometimes

If $TYPO3_CONF_VARS['FE']['defaultTypoScript_constants'] or
$TYPO3_CONF_VARS['FE']['defaultTypoScript_setup'] are set in the Install
tool, cached TS will not be found in cache. This would result in TS
parsing every time when there are USER_INT objects on the page.
Generally it will slow down the page with USER_INT objects by at least
300% comparing to the cached version.

Change-Id: Ia0fd65a35897c71d60c48c0b03098ce67ad16c70
Resolves: #43540
Releases: 4.5, 4.6, 4.7, 6.0, 6.1
Reviewed-on: https://review.typo3.org/16939
Reviewed-by: Adrian Dymorz
Tested-by: Adrian Dymorz
Reviewed-by: Stefan Neufeind
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring
Reviewed-by: Sebastian Michaelsen
Reviewed-by: Dmitry Dulepov
Tested-by: Dmitry Dulepov