Remove @bardenstein from CODEOWNERS

@bardenstein is no longer a member of cisagov.

.github/CODEOWNERS

@@ -3,7 +3,7 @@
 # These owners will be the default owners for everything in the
 # repo. Unless a later match takes precedence, these owners will be
 # requested for review when someone opens a pull request.
-* @bardenstein @BayardJohnson @cisagov/team-ois
+@BayardJohnson @cisagov/team-ois
 
 # These folks own any files in the .github directory at the root of
 # the repository and any of its subdirectories.