Vendoring update for go-discover. (#4412)

* New Providers added and updated vendoring for go-discover

* Vendor.json formatted using make vendorfmt

* Docs/Agent/auto-join: Added documentation for the new providers introduced in this PR

* Updated the golang.org/x/sys/unix in the vendor directory

* Agent: TestGoDiscoverRegistration updated to reflect the addition of new providers

* Deleted terraform.tfstate from vendor.

* Deleted terraform.tfstate.backup

Deleted terraform state file artifacts from unknown runs.

* Updated x/sys/windows vendor for Windows binary compilation

agent/retry_join_test.go

@@ -13,7 +13,7 @@ func TestGoDiscoverRegistration(t *testing.T) {
 		t.Fatal(err)
 	}
 	got := d.Names()
-	want := []string{"aliyun", "aws", "azure", "digitalocean", "gce", "os", "scaleway", "softlayer", "triton"}
+	want := []string{"aliyun", "aws", "azure", "digitalocean", "gce", "os", "packet", "scaleway", "softlayer", "triton", "vsphere"}
 	if !reflect.DeepEqual(got, want) {
 		t.Fatalf("got go-discover providers %v want %v", got, want)
 	}