[tests] verify_checks_test is not being run (or is ignored) on the bots

[pq]

The test verify_checks_test.dart is failing locally but not causing a breakage on the bots. How come?

Local run:

01:11 +5373 -1: custom checks visit_registered_nodes, no_solo_tests, no_trailing_spaces [E]

  Expected: empty
    Actual: [
              AnalysisError:/Users/pquitslund/src/repos/dart/sdk/pkg/linter/lib/src/rules/strict_top_level_inference.dart(1403..1426): Declare 'visit' methods for all registered node types.,
              AnalysisError:/Users/pquitslund/src/repos/dart/sdk/pkg/linter/test/rules/unnecessary_underscores_test.dart(1392..1441): Don't create string literals with trailing spaces in tests.,
              AnalysisError:/Users/pquitslund/src/repos/dart/sdk/pkg/linter/test/rules/unnecessary_underscores_test.dart(1521..1568): Don't create string literals with trailing spaces in tests.
            ]
  

  package:matcher/src/expect/expect.dart 152:31     fail
  package:matcher/src/expect/expect.dart 147:3      _expect
  package:matcher/src/expect/expect.dart 56:3       expect
  test/verify_checks_test.dart 14:7                 main.<fn>.<fn>
verify_checks_test.dart:14
  ===== asynchronous gap ===========================
  package:test_api/src/backend/declarer.dart 229:9  Declarer.test.<fn>.<fn>
  ===== asynchronous gap ===========================
  package:test_api/src/backend/declarer.dart 227:7  Declarer.test.<fn>
  ===== asynchronous gap ===========================
  package:test_api/src/backend/invoker.dart 258:9   Invoker._waitForOutstandingCallbacks.<fn>

/fyi @srawlins: the strict_top_level_inference failure is legit and worth looking at; I'm fixing the unnecessary_underscores_test ones

[srawlins]

Ah I'll look at strict_top_level_inference. Thanks for noticing!

[pq]

@stereotype441 pointed me at this:

https://dart-current-results.web.app/#/filter=pkg/linter/test/verify_checks_test&showAll

which suggests that (at least the last time the tests ran) they passed. The plot thickens!

@athomas?