Update auto-deploy-image to v0.14.0

- Upgraded Helm to 2.16.6
- Set the default deployment API version to apps/v1
- Helm deployments now use --atomic by default
- Do not delete legacy PostgreSQL unless AUTO_DEVOPS_POSTGRES_DELETE_V1
  is set

See https://gitlab.com/gitlab-org/cluster-integration/auto-deploy-image/-/compare/v0.13.0...v0.14.0

changelogs/unreleased/update-ado-image-to-0-14-0.yml

+---
+title: Update auto-deploy-image to v0.14.0 with helm 2.16.6, --atomic deployments
+  and improved kubernetes 1.16 support
+merge_request: 31505
+author:
+type: changed

doc/topics/autodevops/customize.md

@@ -305,6 +305,7 @@ applications.
 |-----------------------------------------|------------------------------------|
 | `ADDITIONAL_HOSTS`                      | Fully qualified domain names specified as a comma-separated list that are added to the Ingress hosts. |
 | `<ENVIRONMENT>_ADDITIONAL_HOSTS`        | For a specific environment, the fully qualified domain names specified as a comma-separated list that are added to the Ingress hosts. This takes precedence over `ADDITIONAL_HOSTS`. |
+| `AUTO_DEVOPS_ATOMIC_RELEASE`            | As of GitLab 13.0, Auto DevOps uses [`--atomic`](https://v2.helm.sh/docs/helm/#options-43) for Helm deployments by default. Set this variable to `false` to disable the use of `--atomic` |
 | `AUTO_DEVOPS_BUILD_IMAGE_CNB_ENABLED`   | When set to a non-empty value and no `Dockerfile` is present, Auto Build builds your application using Cloud Native Buildpacks instead of Herokuish. [More details](stages.md#auto-build-using-cloud-native-buildpacks-beta). |
 | `AUTO_DEVOPS_BUILD_IMAGE_EXTRA_ARGS`    | Extra arguments to be passed to the `docker build` command. Note that using quotes won't prevent word splitting. [More details](#passing-arguments-to-docker-build). |
 | `AUTO_DEVOPS_BUILD_IMAGE_FORWARDED_CI_VARIABLES` | A [comma-separated list of CI variable names](#passing-secrets-to-docker-build) to be passed to the `docker build` command as secrets. |

doc/topics/autodevops/upgrading_postgresql.md

@@ -165,12 +165,14 @@ volume](#retain-persistent-volumes).
 
 TIP: **Tip:** You can also
 [scope](../../ci/environments.md#scoping-environments-with-specs) the
-`AUTO_DEVOPS_POSTGRES_CHANNEL` and `POSTGRES_VERSION` variables to
-specific environments, e.g. `staging`.
+`AUTO_DEVOPS_POSTGRES_CHANNEL`, `AUTO_DEVOPS_POSTGRES_DELETE_V1` and
+`POSTGRES_VERSION` variables to specific environments, e.g. `staging`.
 
 1. Set `AUTO_DEVOPS_POSTGRES_CHANNEL` to `2`. This opts into using the
    newer 8.2.1-based PostgreSQL, and removes the older 0.7.1-based
    PostgreSQL.
+1. Set `AUTO_DEVOPS_POSTGRES_DELETE_V1` to a non-empty value. This flag is a
+   safeguard to prevent accidental deletion of databases.
 1. Set `POSTGRES_VERSION` to `9.6.16`. This is the minimum PostgreSQL
    version supported.
 1. Set `PRODUCTION_REPLICAS` to `0`. For other environments, use

lib/gitlab/ci/templates/Jobs/Deploy.gitlab-ci.yml

 .auto-deploy:
-  image: "registry.gitlab.com/gitlab-org/cluster-integration/auto-deploy-image:v0.13.0"
+  image: "registry.gitlab.com/gitlab-org/cluster-integration/auto-deploy-image:v0.14.0"
 
 review:
   extends: .auto-deploy