Compiler warning in UseCompatibleCmdlets class due unfinished feature with # if DEBUG pragma -> consider removal to allow us to use the /warnaserror compiler option

[bergmeister]

UseCompatibleCmdlets produces a compiler warning when being compiled in Release mode:

UseCompatibleCmdlets.cs(38,27): warning CS0649: Field 'UseCompatibleCmdlets.RuleParameters.mode' is never assigned to, and will always have its default value null [C:\projects\psscriptanalyzer\Rules\Rules.csproj]

This seems to be due a 2 year old, unfinished feature that littered lots of #if DEBUG pragmas in this class. The blame does not tell me a referenced issue, therefore I would argue to remove this compile conditional code.
The benefit of this cleanup would also be that we could use the /warnaserror compiler option for a more rigorous test of code changes in CI.
What do you think @JamesWTruher ?