Show the username as a fallback on feeds if full name is blank (#10461)

Co-authored-by: Lauris BH <lauris@nix.lv>

models/user.go

@@ -712,9 +712,11 @@ func (u *User) DisplayName() string {
 // GetDisplayName returns full name if it's not empty and DEFAULT_SHOW_FULL_NAME is set,
 // returns username otherwise.
 func (u *User) GetDisplayName() string {
-	trimmed := strings.TrimSpace(u.FullName)
-	if len(trimmed) > 0 && setting.UI.DefaultShowFullName {
-		return trimmed
+	if setting.UI.DefaultShowFullName {
+		trimmed := strings.TrimSpace(u.FullName)
+		if len(trimmed) > 0 {
+			return trimmed
+		}
 	}
 	return u.Name
 }