Add a skip condition to all tests slower than 100ms.
This change was made using `gotestsum tool slowest` with data from the
last 3 CI runs of master.
See https://github.com/gotestyourself/gotestsum#finding-and-skipping-slow-tests
With this change:
```
$ time go test -count=1 -short ./agent
ok github.com/hashicorp/consul/agent 0.743s
real 0m4.791s
$ time go test -count=1 -short ./agent/consul
ok github.com/hashicorp/consul/agent/consul 4.229s
real 0m8.769s
```
This ensures the metrics proxy endpoint is ACL protected behind a
wildcard `service:read` and `node:read` set of rules. For Consul
Enterprise these will need to span all namespaces:
```
service_prefix "" { policy = "read" }
node_prefix "" { policy = "read" }
namespace_prefix "" {
service_prefix "" { policy = "read" }
node_prefix "" { policy = "read" }
}
```
This PR contains just the backend changes. The frontend changes to
actually pass the consul token header to the proxy through the JS plugin
will come in another PR.
