Change default repositories for Helm v2

[technosophos]

Per the discussion in the Helm call, this PR is part of the final set of changes to Helm 2. It does the following:

• Init now initializes stable to charts.helm.sh/stable
• There is a flag to disable this behavior and use the old repo
• Every command checks to see if stable or incubator is pointed at the Google buckets. If so, Helm issues a warning.

Obviously this is a breaking change. All of the Helm core maintainers, chart maintainers, and org maintainers have been notified of this, and we agree that it is necessary because Google is going to decommission the existing charts repo.

Note that I have NOT automatically converted existing repository URLs to the new one. I will do that in a separate PR because the core maintainers did not reach a consensus as to whether or not that was appropriate.

NOTE: Race detection on unit tests has been disabled because there is a known issue with current versions of Go and macOS Catalina.

[mattfarina]

@technosophos the error is the one that always catches me... gotta run make docs.

[technosophos]

Oh yeah... Helm 2... :-|

[hickeyma]

I think this will be helpful for users, thanks @technosophos. Just small comment inline and few things as follows:

Do you mind checking in the following files as I think there is still usage of the old storage that might need to be updated: ./docs/using_helm.md, ./cmd/helm/installer/init_test.go and ./pkg/repo/index_test.go

Is this working as expected or should the add also check for the old storage?

$ ./bin/helm repo add old https://kubernetes-charts.storage.googleapis.com
"old" has been added to your repositories

$ ./bin/helm repo list
NAME    	URL                                             
stable  	https://charts.helm.sh/stable                   
local   	http://127.0.0.1:8879/charts                    
jetstack	https://charts.jetstack.io                      
old     	https://kubernetes-charts.storage.googleapis.com

$ ./bin/helm repo remove stable
"stable" has been removed from your repositories

$ ./bin/helm repo add stable https://kubernetes-charts.storage.googleapis.com
"stable" has been added to your repositories

$ ./bin/helm repo update
WARNING: "kubernetes-charts.storage.googleapis.com" is deprecated for "stable" and will be deleted Nov. 13, 2020.
WARNING: You must switch to "https://charts.helm.sh/stable"
Hang tight while we grab the latest from your chart repositories...
...Skip local chart repository
...Successfully got an update from the "jetstack" chart repository
...Successfully got an update from the "stable" chart repository
...Successfully got an update from the "old" chart repository
Update Complete.

$ ./bin/helm install --name mysql-1 stable/mysql
WARNING: "kubernetes-charts.storage.googleapis.com" is deprecated for "stable" and will be deleted Nov. 13, 2020.
WARNING: You must switch to "https://charts.helm.sh/stable"
NAME:   mysql-1
LAST DEPLOYED: Mon Oct 19 11:30:35 2020
NAMESPACE: default
STATUS: DEPLOYED
[...]

[technosophos]

@hickeyma In last Thursday's call, someone remarked that we should be able to add the old repos under a different name, so people could work with the new and the old repos for a bit (I don't know why... but it was one of the goals I wrote down in my notes from that meeting). I supported the behavior by warning on stable/incubator, but allowing for other names like "old"

[technosophos]

I can also backport the error-generating code to Helm 2, but my understanding from the last meeting was that we didn't want to do that for Helm 2. Just Helm 3.

[mattfarina]

lgtm