remove unused writeUtf8 and readUtf8 from TProtocol.py (#3123)

cleanup after #3105

Author: vzhd1701

lib/py/src/protocol/TProtocol.py

@@ -121,9 +121,6 @@ def writeString(self, str_val):
     def writeBinary(self, str_val):
         pass
 
-    def writeUtf8(self, str_val):
-        self.writeString(str_val.encode('utf-8'))
-
     def readMessageBegin(self):
         pass
 
@@ -184,9 +181,6 @@ def readString(self):
     def readBinary(self):
         pass
 
-    def readUtf8(self):
-        return self.readString().decode('utf-8')
-
     def skip(self, ttype):
         if ttype == TType.BOOL:
             self.readBool()