Remove unnecessary copying in transformations

In C++11, string data is always null-terminated[1], and can be
freely modified[2].

[1] https://stackoverflow.com/questions/6077189/will-stdstring-always-be-null-terminated-in-c11
[2] https://stackoverflow.com/questions/38875623/is-it-permitted-to-modify-the-internal-stdstring-buffer-returned-by-operator

CHANGES

@@ -1,6 +1,8 @@
 v3.x.y - YYYY-MMM-DD (to be released)
 -------------------------------------
-   
+ 
+  - Removed unnecessary while processing the transformations.
+    [#2368 - @WGH-, @zimmerle]  
   - auditlog: Computes whether or not to save while loading the rules.
     [@zimmerle]
   - actions: Computes Rule association while loading the rules given a