Temporary revert GPG feature for semver based retagging (#373)

Feature #343 happens to be a breaking change when enabling `.Values.signing` but not specifying
any of the new private key properties. Tag `v6.0.2` is therefore not following semantic versioning.

This temporarily reverts commit b8f0310c43 and a fix-up commit 57a1cd27d9
to retag 6.0.2 as 6.0.3.

Co-authored-by: justusbunsi <sk.bunsenbrenner@gmail.com>
Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/373
Reviewed-by: techknowlogick <techknowlogick@gitea.io>
Reviewed-by: luhahn <luhahn@noreply.gitea.io>

unittests/statefulset/signing-disabled.yaml

@@ -1,40 +0,0 @@
-suite: Statefulset template (signing disabled)
-release:
-  name: gitea-unittests
-  namespace: testing
-templates:
-  - templates/gitea/statefulset.yaml
-  - templates/gitea/config.yaml
-tests:
-  - it: skips gpg init container
-    template: templates/gitea/statefulset.yaml
-    asserts:
-      - notContains:
-          path: spec.template.spec.initContainers
-          any: true
-          content:
-            name: configure-gpg
-  - it: skips gpg env in `init-directories` init container
-    template: templates/gitea/statefulset.yaml
-    set:
-      signing.enabled: true
-    asserts:
-      - contains:
-          path: spec.template.spec.initContainers[0].env
-          content:
-            name: GNUPGHOME
-            value: /data/git/.gnupg
-  - it: skips gpg env in runtime container
-    template: templates/gitea/statefulset.yaml
-    asserts:
-      - notContains:
-          path: spec.template.spec.containers[0].env
-          content:
-            name: GNUPGHOME
-  - it: skips gpg volume spec
-    template: templates/gitea/statefulset.yaml
-    asserts:
-      - notContains:
-          path: spec.template.spec.volumes
-          content:
-            name: gpg-private-key