test(e2e): import lab results from a CSV on an account of its own

The import journey ran on the shared account in both projects, so one
project's duplicate verdict could rest on the other's import. It now runs on
the labs journey's account, emptied first, checks that the dry run writes
nothing and the import writes exactly the accepted row, and finds the result
on the labs page before the second run.

src/__tests__/e2e-critical-no-api-stub-guard.test.ts

@@ -49,7 +49,7 @@ const E2E = join(process.cwd(), "e2e");
  * the set is the release gate, so a journey that loses its tag is a change
  * somebody should see here.
  */
-const CRITICAL_TEST_FLOOR = 12;
+const CRITICAL_TEST_FLOOR = 13;
 
 /** A test whose title literal carries the tag, however the call is spelled. */
 const CRITICAL_TEST =