[!!!][TASK] Remove obsolete APC Cache Backend

All occurrences of APC (without suffix "u") are removed from the
TYPO3 core since APC is discontinued and does not work with
PHP 7.x.

This changes does not affect the PHP OPcache related area.

Releases: master
Resolves: #87583
Change-Id: Ie724f8343dae9bdc4721d35c6d384c1de51f365e
Reviewed-on: https://review.typo3.org/59588


Tested-by: TYPO3com <noreply@typo3.com>
Reviewed-by: Alexander Opitz <opitz.alexander@googlemail.com>
Tested-by: Alexander Opitz <opitz.alexander@googlemail.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>