build: use default cache path for squish craft target instead of separate squish path

[saw-jan]

By using the following as a cache path for linux-gcc-x86_64-squish craft target, we can separately define which Qt version to use for this target and we also omit the necessity of creating separate squish cache path

Packager/CacheVersion = ${Variables:ownCloudVersion}/Qt_${linux-gcc-x86_64-squish-BlueprintSettings:libs/qt6.version}_${Variables:CachePatchLvl}

This targets the linux cache folder of defined Qt version for libraries and we no longer require squish cache folder

[saw-jan]

@DeepDiver1975 Could you check if this is valid and doesn't affect anything else?
I tested with craft and the the libraries are downloaded from the correct cache path

If we merge this then we can also remove these:

https://gitea.owncloud.services/client/build-craft-cache/src/commit/df5426a4b3d7c2c4f28e288a398366eda9feb17b/.drone.star#L10

This also?: https://gitea.owncloud.services/client/build-craft-cache/src/commit/df5426a4b3d7c2c4f28e288a398366eda9feb17b/craft_override.ini#L24-L32

[saw-jan]

this is no longer required.
See #12268