Cisco Catalyst stack switches model names

Issue description:

Some standalone Cisco Catalyst switches report "stack" sysObjectIDs, hence Discovery also reports "stack" model, like "Catalyst 29xx Switch Stack".

For example, according to the CISCO-PRODUCTS-MIB sysObjectID 1.3.6.1.4.1.9.1.1208 is dedicated to "cat29xxStack".

In this case, Discovery reports model according to the CISCO-PRODUCTS-MIB, i.e. for 1.3.6.1.4.1.9.1.1208 the model will be "Catalyst 29xx Switch Stack".

The update made in TKU 2019 March is fixing this issue, so the model for the standalone devices will not be "stack"-like.