[BUGFIX] Allow TYPO3_CONTEXT to be set from Apache2 with suexec support

Apache2 suexec support prefixes environment variables with HTTP_ in order
to whitelist environment variables - this is what TYPO3 is using for TYPO3_CONTEXT.

Resolves: #90145
Releases: master, 9.5
Change-Id: I069949578c2467436fca568504dcda84d16df8fa
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/63627


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Susanne Moog <look@susi.dev>
Tested-by: Daniel Goerz <daniel.goerz@posteo.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Susanne Moog <look@susi.dev>
Reviewed-by: Daniel Goerz <daniel.goerz@posteo.de>