After fixing that bug I uncovered a couple more:
Fix an issue where we might try to cross sign a cert when we never had a valid root.
Fix a potential issue where reconfiguring the CA could cause either the Vault or AWS PCA CA providers to delete resources that are still required by the new incarnation of the CA.
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
```
