upgrade: speed up when we have only nodemap to downgrade

The test change is wrong.
13 jobs for topic/default/upgrade-refactor in 33 minutes and 31 seconds (queued for 49 seconds)
Status Name Job ID Coverage
  Tests
passed checks-py2 #166530

00:03:40

passed checks-py3 #166531

00:03:22

passed rust-cargo-test-py2 #166532

00:02:25

passed rust-cargo-test-py3 #166533

00:03:30

passed test-py2 #166534

00:29:02

passed test-py2-chg #166540

00:25:49

passed test-py2-pure #166536

00:20:22

passed test-py2-rust #166538

00:21:33

passed test-py3 #166535

00:24:03

passed test-py3-chg #166541

00:15:46

passed test-py3-pure #166537

00:14:32

passed test-py3-rust #166539

00:23:10

 
  Phabricator
passed phabricator-refresh #166542

00:00:22