[BUGFIX] Add additional TS for contentRenderingTemplates loaded by file

Loading extensions TS, that provide contentRenderingTemplates, like
css_styled_content, using INCLUDE_TYPOSCRIPT was fixed in
https://review.typo3.org/#/c/21679/.

Since making TS content templates more flexible in
https://review.typo3.org/#/c/27587/ the contentRenderingTemplates wasn't
added to "defaultTypoScript_setup." and "defaultTypoScript_constants."
arrays anymore and breaks the mentioned fix.

Solution is to check the required key in contentRenderingTemplates and
add the defaultContentRendering string now.

Resolves: #59318
Releases: 6.2
Change-Id: I8a367f462f304e07bbcec99fd26818bc98148eb4
Reviewed-on: https://review.typo3.org/30544
Reviewed-by: Benjamin Mack
Reviewed-by: Krzysztof Adamczyk
Tested-by: Krzysztof Adamczyk
Reviewed-by: Tymoteusz Motylewski
Tested-by: Tymoteusz Motylewski
Reviewed-by: Steffen Ritter
Tested-by: Steffen Ritter