Increase testability of shell scripts (#752)

This is a preparation for #724 (bash script testing) which would be too complex to review if done there.

Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/752
Co-authored-by: justusbunsi <sk.bunsenbrenner@gmail.com>
Co-committed-by: justusbunsi <sk.bunsenbrenner@gmail.com>

templates/gitea/deployment.yaml

@@ -107,6 +107,10 @@ spec:
               value: /data
             - name: GITEA_TEMP
               value: /tmp/gitea
+            - name: TMP_EXISTING_ENVS_FILE
+              value: /tmp/existing-envs
+            - name: ENV_TO_INI_MOUNT_POINT
+              value: /env-to-ini-mounts
             {{- if .Values.deployment.env }}
             {{- toYaml .Values.deployment.env | nindent 12 }}
             {{- end }}
@@ -149,6 +153,8 @@ spec:
           env:
             - name: GNUPGHOME
               value: {{ .Values.signing.gpgHome }}
+            - name: TMP_RAW_GPG_KEY
+              value: /raw/private.asc
           volumeMounts:
             - name: init
               mountPath: /usr/sbin