[BUGFIX] Ensure PackageManager scans every possible directory

If a scanAvailablePackages() of the PackageManager is triggered, we
need to make sure all possible packagesBasePaths are taken into account.
As new extensions might have been downloaded, we need to re-check those
possible paths unless all were found.

Resolves: #83560
Releases: master, 8.7
Change-Id: I4a65a2f384163b6a3cc3071711e80d88eaf22971
Reviewed-on: https://review.typo3.org/55356


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Nicole Cordes <typo3@cordes.co>
Tested-by: Nicole Cordes <typo3@cordes.co>
Reviewed-by: Helmut Hummel <typo3@helhum.io>
Tested-by: Helmut Hummel <typo3@helhum.io>