[TASK] Clean up buildBaseTcaFromSingleFiles()

The method uses two different approaches to get a list of active
packages, this is cleaned up to use the package manager only.

Change-Id: Ifc73d36ed0020914b0f7cf0b479010f91d1eba7f
Resolves: #60121
Related: #60120
Related: #59770
Releases: 6.3, 6.2
Reviewed-on: https://review.typo3.org/31360
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring