Remove duplicate utility bill variables

[cpaulgilman]

Fixes NatLabRockies/SAM#1879

Goes with NatLabRockies/SAM#2009, see that PR for details.

[sjanzou]

Sorry you had to change 47 test files!

[brtietz]

I know this is a nitpick given the current release plan, but variable changes like this should be merged into develop, not patch.

[brtietz]

I ran find and replace a few times to identify potential errors, and turned up the following:

(sys_system instead of just sys)

There were also a few hits in the PySAM examples:

What is the appropriate time to update those?

[cpaulgilman]

There were also a few hits in the PySAM examples:

This should be addressed in NatLabRockies/pysam#185

[cpaulgilman]

(sys_system instead of just sys)

Good find. Thanks! Should be fixed in 0de61b7.

I also noticed one other set of variables that use "system" instead of "sys" in this context:

year1_monthly_peak_wo_system
year1_monthly_use_wo_system
year1_monthly_peak_w_system
year1_monthly_use_w_system

@brtietz, is it worth changing that? These variables seem to only be used as outputs to utilityrate5, so changing their names should have no impact on other SSC/SAM code and samples, but will affect any SDK/PySAM code out in the world that refers to those outputs.