tests/provider: Temporarily disable staticcheck in golangci-lint conf…

…iguration by default

We may want to wait until staticcheck 2019.1.1:

* golangci/golangci-lint#445
* https://github.com/dominikh/go-tools/releases/tag/2019.1.1

Still trying to workaround memory issues in TravisCI:

```
$ make lint
==> Checking source code against linters...
fatal error: runtime: out of memory```
```

.golangci.yml

@@ -11,7 +11,6 @@ linters:
     - gosimple
     - ineffassign
     - misspell
-    - staticcheck
     - structcheck
     - unconvert
     - unused