Change the mapped sector of the company fin data

[Clare2D]

As @2diiKlaus flagged, the fin sector overrides of the mapped sector in the comp_fin_data is not occurring. This should be part of the work that @cjyetman is doing to refactor this code.

Specifically this means:

• merging in the fin sector overrides as is done for the security level financial data.

[2diiKlaus]

Not even sure if it is done for securities well enough - could check listed equity instruments for :
ThyssenKrupp, Siemens, 3m co, ... basically ICB = "Diversified Industrials" as these are classified as Power which is wrong in almost all cases

[cjyetman]

this will probably be dealt with here 2DegreesInvesting/data_preparation/issues/14