tests: Remove unnecessary @slow decorators.

This is part of addressing #1478.

zerver/tests/test_home.py

@@ -22,7 +22,6 @@ from zerver.models import (
 from zerver.views.home import home, sent_time_in_epoch_seconds
 
 class HomeTest(ZulipTestCase):
-    @slow('big method')
     def test_home(self):
         # type: () -> None
 

zerver/tests/test_messages.py

@@ -419,7 +419,6 @@ class PersonalMessagesTest(ZulipTestCase):
         self.assertEqual(most_recent_message(sender).recipient, recipient)
         self.assertEqual(most_recent_message(receiver).recipient, recipient)
 
-    @slow("assert_personal checks several profiles")
     def test_personal(self):
         # type: () -> None
         """
@@ -428,7 +427,6 @@ class PersonalMessagesTest(ZulipTestCase):
         self.login(self.example_email("hamlet"))
         self.assert_personal(self.example_email("hamlet"), self.example_email("othello"))
 
-    @slow("assert_personal checks several profiles")
     def test_non_ascii_personal(self):
         # type: () -> None
         """

zerver/tests/test_subs.py

@@ -1888,7 +1888,6 @@ class SubscriptionAPITest(ZulipTestCase):
         # Make sure we don't make O(streams) queries
         self.assert_length(queries, 19)
 
-    @slow("common_subscribe_to_streams is slow")
     def test_subscriptions_add_for_principal(self):
         # type: () -> None
         """
@@ -1900,7 +1899,6 @@ class SubscriptionAPITest(ZulipTestCase):
         invite_streams = self.make_random_stream_names(current_streams)
         self.assert_adding_subscriptions_for_principal(invitee_email, invitee_realm, invite_streams)
 
-    @slow("common_subscribe_to_streams is slow")
     def test_subscriptions_add_for_principal_invite_only(self):
         # type: () -> None
         """
@@ -1913,7 +1911,6 @@ class SubscriptionAPITest(ZulipTestCase):
         self.assert_adding_subscriptions_for_principal(invitee_email, invitee_realm, invite_streams,
                                                        invite_only=True)
 
-    @slow("common_subscribe_to_streams is slow")
     def test_non_ascii_subscription_for_principal(self):
         # type: () -> None
         """
@@ -2561,7 +2558,6 @@ class GetSubscribersTest(ZulipTestCase):
 
         test_admin_case()
 
-    @slow("common_subscribe_to_streams is slow")
     def test_gather_subscriptions_mit(self):
         # type: () -> None
         """