Remove constant_time_prepare

We no longer see any usage of the function in openstack namespace so
can remove it now.

Related-Bug: #2081732
Change-Id: I3c6205ca518dc9c0fd35680b5559f9fd75f5879a

oslo_utils/secretutils.py

@@ -21,27 +21,12 @@ Secret utilities.
 import ctypes
 import ctypes.util
 import hashlib
-import hmac
 import secrets
 import string as _string
 
 import debtcollector.removals
 
 
-@debtcollector.removals.remove(message='Use hmac.compare_digest instead',
-                               category=DeprecationWarning)
-def constant_time_compare(*args, **kwargs):
-    """Return True if both string or binary inputs are equal, otherwise False.
-
-    This function should take a constant amount of time regardless of
-    how many characters in the strings match. This function uses an
-    approach designed to prevent timing analysis by avoiding
-    content-based short circuiting behaviour, making it appropriate
-    for cryptography.
-    """
-    return hmac.compare_digest(*args, **kwargs)
-
-
 @debtcollector.removals.remove(message='Use hashlib.md5 instead',
                                category=DeprecationWarning)
 def md5(string=b'', usedforsecurity=True):

releasenotes/notes/remove-constant_time_compare-afac749af5c57620.yaml

@@ -0,0 +1,5 @@
+---
+upgrade:
+  - |
+    The deprecated ``oslo_utils.secretutils.constant_time_compare`` function
+    has been removed.