MCOL-5199 This patch solves the overal performance degradation introduced with a new way of char columns hashing

in aggregation code
The patch disables padding that forces hasher to calculate over the whole 2k buffer. This patch also moves hashing code
into the common place where it belongs.

utils/common/conststring.h

@@ -66,6 +66,13 @@ class ConstString
     }
     return *this;
   }
+  ConstString& rtrimSpaces()
+  {
+    for (; mLength && mStr[mLength - 1] == ' '; --mLength)
+    {
+    }
+    return *this;
+  }
 };
 
 }  // namespace utils