YAMLSelector bugfix for Knative RPS

[cvetkovic]

Removing redundant fields that added consistency problems.

[leokondrashov]

Looks fine to me right now.

However, I would argue that we should make it possible to create Azure trace parser and rps generator without passing knative-specific and/or dirigent-specific arguments. At least, we should extract parsing the trace/generating the function inv data from the filling all of the necessary fields in the Function structure.

[cvetkovic]

I wanted to remove the YAMLSelector from the Function specification, but vSwarm traces rely on this since functions do not share the YAML file, therefore I left it.

[leokondrashov]

My point was that we can generate functions with all invocations first and then fill the rest of the fields in a separate method. That would let us generate the invocations without requiring any system-specific parameters/arguments since it is system-agnostic. The function structure doesn't need to be changed; we can leave the fields as nils during the invocation generation phase.