'argocd-repo-server' don't cleanup helm temp files

[alexmt]

Describe the bug
The argocd-repo-server creates temp helm home directory on every manifest generation and never delete it. As a result /tmp directory keeps growing and eventually service became unstable.

To Reproduce
Steps to reproduce the behavior:

1. Create helm based application
2. Reconcile application multiple times
3. Check /tmp directory.

Expected behavior
The argocd-repo-server should delete temp directory once it is not required any more.