Releases prior to 3.3.0 no longer resolve

Describe the bug References to older chart versions no longer resolve

I noticed the index.yaml was recently completely re-built (deleted, then re-added), and older releases now have a new URL like:

https://launchdarkly.github.io/ld-relay-helm/helm-repo/ld-relay-3.1.0.tgz

note the /helm-repo/ component, which doesn't seem to exist in the repo itself. These URLs 404 when fetched

but the newest release 3.3.0 has a URL like:

https://launchdarkly.github.io/ld-relay-helm/ld-relay-3.3.0.tgz

which works.

To reproduce

# Chart.yaml
---
apiVersion: v2
name: launchdarkly-relay-proxy
description: |
  The LaunchDarkly Relay Proxy is a small Go application that runs on your own infrastructure. It connects to the
  LaunchDarkly streaming API and proxies that connection to clients within your organization's network.
type: application
version: 1.0.0
appVersion: '1.0.0'
dependencies:
  - name: ld-relay
    version: 3.1.0
    repository: https://launchdarkly.github.io/ld-relay-helm

$ helm repo add launch-darkly-relay https://launchdarkly.github.io/ld-relay-helm
...

$ helm dependency build .                                                       
Hang tight while we grab the latest from your chart repositories...
...Successfully got an update from the "launch-darkly-relay" chart repository
Update Complete. ⎈Happy Helming!⎈
Saving 1 charts
Downloading ld-relay from repo https://launchdarkly.github.io/ld-relay-helm
Save error occurred:  could not download https://launchdarkly.github.io/ld-relay-helm/helm-repo/ld-relay-3.1.0.tgz: failed to fetch https://launchdarkly.github.io/ld-relay-helm/helm-repo/ld-relay-3.1.0.tgz : 404 Not Found
Error: could not download https://launchdarkly.github.io/ld-relay-helm/helm-repo/ld-relay-3.1.0.tgz: failed to fetch https://launchdarkly.github.io/ld-relay-helm/helm-repo/ld-relay-3.1.0.tgz : 404 Not Found

Expected behavior Expected old chart versions to be able to be resolved when listed as a dependency

Logs n/a

Helm chart version I've verified that all versions < 3.3.0 have the broken URL (/helm-repo/ component)

Relay proxy configuration, developer tools n/a

Additional context n/a

launchdarkly / ld-relay-helm

Releases prior to 3.3.0 no longer resolve #62