[BUGFIX] Skip -1 as language column in fluid based page layout

Since #90854 the siteLanguages array also contains the
-1 language which must be skipped because it otherwise
falls back and generates another default language column.

Resolves: #91986
Relates: #90854
Releases: master, 10.4
Change-Id: I5b1388bb9a8af7a3c14827d3aa714e23d670dcd1
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/65545


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Riccardo De Contardi <erredeco@gmail.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Daniel Goerz <daniel.goerz@posteo.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Daniel Goerz <daniel.goerz@posteo.de>