Skaffold does not delete unused manifests if they have been removed from skaffold.yaml when deploy

### Expected behavior

Skaffold should know which manifests/helm charts have been deleted from `skaffold.yaml` when deploy

### Actual behavior

If a manifest/helm chart is removed from skaffold.yaml file, after running `skaffold deploy` the deleted manifests will not be deleted from the cluster

### Information

- Skaffold version: v2.8.0
- Installed via: Homebrew

### Steps to reproduce the behavior

Suppose I have this config:

```yaml
apiVersion: skaffold/v4beta7
kind: Config
deploy:
helm:
releases:
- name: postgres
repo: https://charts.bitnami.com/bitnami
remoteChart: postgresql
- name: mongo
repo: https://charts.bitnami.com/bitnami
remoteChart: mongodb
```

After run `skaffold deploy`, the 2 charts will successfully be installed on the cluster.

Now, suppose that I don't want the mongo chart anymore on my cluster, so I would delete it from my config:

```yaml
apiVersion: skaffold/v4beta7
kind: Config
deploy:
helm:
releases:
- name: postgres
repo: https://charts.bitnami.com/bitnami
remoteChart: postgresql
# - name: mongo
# repo: https://charts.bitnami.com/bitnami
# remoteChart: mongodb
```

If I run `skaffold deploy`, obviosly skaffold will not delete the mongo chart.

Is there a way to keep track the deployed skaffold manifests in order to choose if you want to delete them or not based on the `skaffold.yaml` file?

It will be very useful to have this feature in order to use a GitOps approach without using other tools.