Verify the Helm Upgrade procedure still works

[zaharidichev]

Currently the docs prscribe that helm upgrade linkerd2 linkerd/linkerd2 --reuse-values should be used when ugrading. However this does not work at the moment. When upgrading from 2.6 to edge things break and helm is complaining that its missing values. We need to investigate what is happening and what is the proper upgrade process as quite a bit of things have moved around/changed in the charts. For reference this works:

helm upgrade linkerd2 \
                           --set-file global.identityTrustAnchorsPEM=ca.crt \
                           --set-file identity.issuer.tls.crtPEM=issuer.crt \
                           --set-file identity.issuer.tls.keyPEM=issuer.key \
                           --set identity.issuer.crtExpiry=$exp \
                           linkerd-edge/linkerd2  --atomic

Also some more information around the use of --reuse-values and --reset-values can be found right here: