Update Interop doc

The commit replaces DefCore committee (a former name) by
Interop Working Group (the current name) and updates a few
more old interop references.

Change-Id: I578a21d610b5b680b4549bf34e1857307a1b8e74

Author: kopecmartin

doc/source/contributor/testing.rst

@@ -121,6 +121,7 @@ services and a database, with minimal stubbing of nova internals.
 Interoperability tests
 -----------------------
 
-The DefCore committee maintains a list that contains a subset of Tempest tests.
-These are used to verify if a particular Nova deployment's API responds as
-expected. For more details, see: https://opendev.org/osf/interop
+The Interop Working Group maintains a list that contains a subset of Tempest
+tests. These are used to verify if a particular Nova deployment's API responds
+as expected. For more details, see:
+https://docs.opendev.org/openinfra/interop/latest/

doc/source/user/feature-classification.rst

@@ -139,7 +139,7 @@ rating for each feature group.
 .. note::
 
    Although having some similarities, this list is not directly related
-   to the DefCore effort.
+   to the Interop effort.
 
 **Feature Group ratings:**