MCO-136 disable Style/SymbolProc

Style/SymbolProc prefers

    things.map { |t| t.to_i }

be expressed as:

    things.map(&:to_i)

It's only the smallest of performance gains, but the readbility hit is real.

.rubocop.yml

@@ -387,6 +387,10 @@ Style/SingleLineMethods:
 Style/SpecialGlobalVars:
   Enabled: false
 
+# DISABLED - minor performance gain for major readability hit
+Style/SymbolProc:
+  Enabled: false
+
 Style/TrivialAccessors:
   Enabled: false