Use bare algorithm pointers in AlgResourcePool

The following discussion from !1149 (merged) should be addressed:

• @clemenci started a discussion:

  This change, as is, introduces an asymmetry wrt to the single thread case:

  • single thread: algorithms are destroyed during AlgorithmManager finalization (before services are finalized)
  • multi thread: algorithms are destroyed during AlgResourcePool finalization (while services are being finalized)

  As AlgResourcePool does not need to access the algorithms during finalization, it should be enough to use list of pointers instead of list of SmartIFs.