test: shorten some test names

This helps us fit within 80 columns pytest output when not displaying to
a terminal (like in GitHub Actions).

Author: allisonkarlitskaya

test/test_regexp.py

@@ -80,19 +80,19 @@
         }
     ),
 
-    'change password old prompt': (
+    'change pw old': (
         r"""Enter lis@srv's old password: """,
         'AskpassPrompt', {
         }
     ),
 
-    'change password new prompt': (
+    'change pw new': (
         r"""Enter lis@srv's new password: """,
         'AskpassPrompt', {
         }
     ),
 
-    'change password retype prompt': (
+    'change pw verify': (
         r"""Retype lis@srv's new password: """,
         'AskpassPrompt', {
         }