Fix domain macro (#560)

### Description of the change

This supersedes #359 by fixing the fallback domain value when no ingress host is defined.

Memcached is not used anymore. PostgreSQL macro has already been fixed otherwise.

### Checklist

- [x] Templating unittests are added

Co-authored-by: pat-s <pat-s@noreply.gitea.com>
Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/560
Reviewed-by: pat-s <pat-s@noreply.gitea.com>
Co-authored-by: justusbunsi <sk.bunsenbrenner@gmail.com>
Co-committed-by: justusbunsi <sk.bunsenbrenner@gmail.com>

templates/_helpers.tpl

@@ -151,7 +151,7 @@ app.kubernetes.io/instance: {{ .Release.Name }}
 {{- end -}}
 
 {{- define "gitea.default_domain" -}}
-{{- printf "%s-gitea.%s.svc.%s" (include "gitea.fullname" .) .Release.Namespace .Values.clusterDomain | trunc 63 | trimSuffix "-" -}}
+{{- printf "%s-http.%s.svc.%s" (include "gitea.fullname" .) .Release.Namespace .Values.clusterDomain -}}
 {{- end -}}
 
 {{- define "gitea.ldap_settings" -}}