[BUGFIX] Install Tool: [SYS][displayErrors] text names wrong default value

displayErrors is "0" with the Production Application Context / Preset,
and is set to "1" for Debugging / Development Context and its Preset.
"-1" is stated as the "default" setting but overriden after a fresh
installation.

The install tool option claims that "-1" is the default, but it really isn't
the default per-se, but only if LocalConfiguration.php does not have the
setting used at all. Thus, the info "Default value" is removed.

Resolves: #67553
Releases: master
Change-Id: I98665ba33165f98788d89adc1536f6df0060a5f5
Reviewed-on: http://review.typo3.org/43878


Reviewed-by: Michael Oehlhof <typo3@oehlhof.de>
Tested-by: Michael Oehlhof <typo3@oehlhof.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>