[BUGFIX] Avoid overly large regex in substituteMarkerArrayCached

Fetch the actually used markers from the content and only
generate the replace regex for those.
This avoids problems where 1000 markers may be passed in,
but only 10 are actually used.

Resolves: #44270
Releases: master, 6.2
Change-Id: I05f60960949e945249b045a8ae8e8430f7d8f7e6
Reviewed-on: https://review.typo3.org/45097


Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>