use the right way to unescape line string

Reference https://github.com/ansible/ansible/issues/10864

files/lineinfile.py

@@ -22,7 +22,6 @@
 import re
 import os
 import pipes
-import codecs
 import tempfile
 
 DOCUMENTATION = """
@@ -370,14 +369,6 @@ def main():
 
         line = params['line']
 
-        # Replace escape sequences like '\n' while being sure 
-        # not to replace octal escape sequences (\ooo) since they
-        # match the backref syntax.
-        if backrefs:
-            line = re.sub(r'(\\[0-9]{1,3})', r'\\\1', line)
-
-        line = codecs.escape_decode(line)[0]
-
         present(module, dest, params['regexp'], line,
                 ins_aft, ins_bef, create, backup, backrefs)
     else: