Drop unneeded link to GaudiPluginService in LoKiFunctorsCache
Backport of part of !2690 (merged), needed to compile functor caches with Gaudi new CMake configuration (gaudi/Gaudi!986 (merged)).
Backport of part of !2690 (merged), needed to compile functor caches with Gaudi new CMake configuration (gaudi/Gaudi!986 (merged)).