Remove portfolio optimisation shortcut

[DidierRLopes]

• Fixes [Bug] When entering the comparison analysis menu with a loaded ticker containing a suffix, the suffix is not passed through to the ticker in the menu.  #2257
• Remove po shortcut from ca controller

[JerBouma]

Some others places po is mentioned where it shouldn't be (could you remove them too @DidierRLopes?):

• options/screener/screener_controller.py
• stocks/screener/screener_controller.py

Background why we remove this integration:

Portfolio optimization is not a straightforward thing. All of the parameters you can define within each po command are massive considerations that have an incredibly large impact on the portfolio. E.g. we currently have defaults set but they are not based on any financial theory that this is the right approach. Why 3y of historical data? How do returns of the past get factored in? What risk measure? What covariance matrix? What significance level? Want to go short or only long? I can go on. Simply calling maxsharpe therefore has no meaning whatsoever unless you thought of it extensively.

We do not want to give our users the impression we believe that integrations with screeners and/or comparison analysis lead to effective and/or sound portfolios. This requires 10 times much more thought than this integration indicates. Furthermore, you don't tend to optimise a non-existing portfolio in the first place.

[DidierRLopes]

@JerBouma done!

[JerBouma]

Looks good to me.