Skip long cmd/tendermint/commands tests in -short mode

I added checks against testing.Short for tests that took longer than
about one second on my machine. Running with -short reduces the test
time of cmd/tendermint/commands from about 5.8s to about 0.5s.

cmd/tendermint/commands/rollback_test.go

@@ -15,6 +15,10 @@ import (
 )
 
 func TestRollbackIntegration(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping test in short mode")
+	}
+
 	var height int64
 	dir := t.TempDir()
 	ctx, cancel := context.WithCancel(context.Background())