Remove calls to deprecated function getService from AbstractAnalysis

[xispa]

Description of the issue/feature this PR addresses

Removes all calls to the deprecated function getService from AbstractAnalysis. This function was returning the Analysis Service from which an Analysis was created. After the architectural refactoring of Analysis, objects from type Analysis acquire the values from the original AnalysisService without the need of maintaining this relationship (that had an overhead because of an HistoryAwareReferenceField was required). getService function was labelled as deprecated then and was returing the Analysis itself. With this Pull Request, the calls to getService have been removed and are using the fields provided by the Analysis object itself.

Current behavior before PR

Deprecation warnings because of the use of getService function in logs.

Desired behavior after PR is merged

No deprecation warnings in logs because the function getService is no longer used in the basecode.

--
I confirm I have tested this PR thoroughly and coded it according to PEP8
and Plone's Python styleguide standards.

[ramonski]

Great PR and easy to understand. So the Analysis always is a "copy" of the AS at the moment in time when it was used for an AR, but maintains a reference to the newest version of the AS, right?

[xispa]

Yes @ramonski, the Analysis is a "copy" of the AnalysisService that was used as the "template" for its creation. Even though, maintans a reference to the newest AS (not the one was used as the "template") thanks to getAnalysisService function.