MM-26015: ensure admin retains permissions to team after being removed from a team (#14961)

Summary:
Ensure admin retains permissions to team after being removed from a team

Ticket Link:
https://mattermost.atlassian.net/browse/MM-26015

app/authorization.go

@@ -146,23 +146,10 @@ func (a *App) HasPermissionToTeam(askingUserId string, teamId string, permission
 	if teamId == "" || askingUserId == "" {
 		return false
 	}
-
-	teamMember, err := a.GetTeamMember(teamId, askingUserId)
-	if err != nil {
-		return false
+	teamMember, _ := a.GetTeamMember(teamId, askingUserId)
+	if teamMember != nil && teamMember.DeleteAt == 0 {
+		return a.RolesGrantPermission(teamMember.GetRoles(), permission.Id)
 	}
-
-	// If the team member has been deleted, they don't have permission.
-	if teamMember.DeleteAt != 0 {
-		return false
-	}
-
-	roles := teamMember.GetRoles()
-
-	if a.RolesGrantPermission(roles, permission.Id) {
-		return true
-	}
-
 	return a.HasPermissionTo(askingUserId, permission)
 }
 

app/authorization_test.go

@@ -52,4 +52,10 @@ func TestHasPermissionToTeam(t *testing.T) {
 	th.RemoveUserFromTeam(th.BasicUser, th.BasicTeam)
 
 	assert.False(t, th.App.HasPermissionToTeam(th.BasicUser.Id, th.BasicTeam.Id, model.PERMISSION_LIST_TEAM_CHANNELS))
+
+	th.LinkUserToTeam(th.SystemAdminUser, th.BasicTeam)
+	assert.True(t, th.App.HasPermissionToTeam(th.SystemAdminUser.Id, th.BasicTeam.Id, model.PERMISSION_LIST_TEAM_CHANNELS))
+	th.RemoveUserFromTeam(th.SystemAdminUser, th.BasicTeam)
+	// This used to fail before MM-26015
+	assert.True(t, th.App.HasPermissionToTeam(th.SystemAdminUser.Id, th.BasicTeam.Id, model.PERMISSION_LIST_TEAM_CHANNELS))
 }