[BUGFIX] Parsetime: config.debug should override LocalConfiguration

Parsetime is output either if config.debug is set or if FE-debug
is activated in LocalConfiguration. Allow to explicitly override
(set to 0) the debugging in TS for cases where you want to output
page-objects like a JSON-page or so where Parsetime leads to
problems.

Change-Id: Ie5588218694219c13f136b5ac928e697ca472cfb
Resolves: #57202
Releases: 6.2, 6.1
Reviewed-on: https://review.typo3.org/28667
Reviewed-by: Markus Klein
Tested-by: Markus Klein