Remove remaining t.Fatal from the codebase (#13876)

* Remove remaining t.Fatal from the codebase

* Fix job_store test

* Address review comments

* Remove comments

app/channel_test.go

@@ -405,7 +405,7 @@ func TestAddUserToChannelCreatesChannelMemberHistoryRecord(t *testing.T) {
 
 	// the user leaves that channel
 	if err := th.App.LeaveChannel(publicChannel.Id, th.BasicUser.Id); err != nil {
-		t.Fatal("Failed to remove user from channel. Error: " + err.Message)
+		require.Fail(t, "Failed to remove user from channel. Error: " + err.Message)
 	}
 	histories = store.Must(th.App.Srv().Store.ChannelMemberHistory().GetUsersInChannelDuring(model.GetMillis()-100, model.GetMillis()+100, publicChannel.Id)).([]*model.ChannelMemberHistoryResult)
 	assert.Len(t, histories, 1)
@@ -477,9 +477,8 @@ func TestAddChannelMemberNoUserRequestor(t *testing.T) {
 
 	// create a user and add it to a channel
 	user := th.CreateUser()
-	if _, err := th.App.AddTeamMember(th.BasicTeam.Id, user.Id); err != nil {
-		t.Fatal("Failed to add user to team. Error: " + err.Message)
-	}
+	_, err := th.App.AddTeamMember(th.BasicTeam.Id, user.Id)
+	require.Nil(t, err)
 
 	groupUserIds := make([]string, 0)
 	groupUserIds = append(groupUserIds, th.BasicUser.Id)
@@ -488,7 +487,7 @@ func TestAddChannelMemberNoUserRequestor(t *testing.T) {
 	channel := th.createChannel(th.BasicTeam, model.CHANNEL_OPEN)
 	userRequestorId := ""
 	postRootId := ""
-	_, err := th.App.AddChannelMember(user.Id, channel, userRequestorId, postRootId)
+	_, err = th.App.AddChannelMember(user.Id, channel, userRequestorId, postRootId)
 	require.Nil(t, err, "Failed to add user to channel.")
 
 	// there should be a ChannelMemberHistory record for the user