chore(dvcr): remove unsupported s3 feature

[universal-itengineer]

Description

Remove the unsupported legacy S3 object storage configuration for DVCR.

The following options are dropped from the module config:

• dvcr.storage.objectStorage.s3.accessKey
• dvcr.storage.objectStorage.s3.secretKey
• dvcr.storage.objectStorage.s3.region
• dvcr.storage.objectStorage.s3.regionEndpoint
• dvcr.storage.objectStorage.s3.bucket

Concretely this PR:

• Removes the ObjectStorage/s3 branch from openapi/config-values.yaml and its Russian localization in openapi/doc-ru-config-values.yaml. dvcr.storage.type now allows only PersistentVolumeClaim.
• Drops the REGISTRY_STORAGE_S3_* environment variables and the object-storage based HA branch from templates/dvcr/_helpers.tpl, and removes the now-unused local dvcr.helm_lib_is_ha_to_value helper (DVCR PDB uses an explicit minAvailable: 0).
• Removes the dvcr-object-storage-credentials Secret (s3AccessKey/s3SecretKey) from templates/dvcr/secret.yaml.

A second commit adds non-chart directories (.github, api, hack, src, test, tools, tmp, CHANGELOG) to .helmignore so that helm template/helm package no longer fails on files exceeding Helm's 5 MB per-file limit (e.g. the cloned tools/kubeconform/kubeconform.git fixtures) during local render validation.

Why do we need it, and what problem does it solve?

The S3 object storage path was unsupported legacy configuration that is no longer maintained. Keeping it in the public schema and Helm templates was misleading and added dead code paths. Removing it keeps DVCR storage configuration limited to the supported PersistentVolumeClaim mode.

What is the expected result?

• The module config schema accepts only dvcr.storage.type: PersistentVolumeClaim.
• The DVCR chart renders without any S3-related env, Secret, or HA branch.
• Local kubeconform render validation passes (115 valid resources, 0 errors, 0 invalid; remaining "no schema" items are pre-existing CRDs without downloaded schemas).

Checklist

• The code is covered by unit tests.
• e2e tests passed.
• Documentation updated according to the changes.
• Changes were tested in the Kubernetes cluster manually.

Changelog entries

section: dvcr
type: chore
summary: Remove unsupported legacy S3 object storage configuration for DVCR.