fix test-runner-reporters #45929

# Subtest: should support a 'mjs' file as a custom reporter
20:32:33         not ok 11 - should support a 'mjs' file as a custom reporter
20:32:33           ---
20:32:33           duration_ms: 415.375369
20:32:33           failureType: 'testCodeFailure'
20:32:33           error: |-
20:32:33             Expected values to be strictly equal:
20:32:33             + actual - expected
20:32:33             
20:32:33             + 'custom.mjs {"test:start":5,"test:pass":2,"test:fail":3,"test:plan":3,"test:diagnostic":3}'
20:32:33             - 'custom.mjs {"test:start":5,"test:pass":2,"test:fail":3,"test:plan":3,"test:diagnostic":7}'
20:32:33           code: 'ERR_ASSERTION'
20:32:33           expected: 'custom.mjs {"test:start":5,"test:pass":2,"test:fail":3,"test:plan":3,"test:diagnostic":7}'
20:32:33           actual: 'custom.mjs {"test:start":5,"test:pass":2,"test:fail":3,"test:plan":3,"test:diagnostic":3}'
20:32:33           operator: 'strictEqual'
20:32:33           stack: |-
20:32:33             Object.<anonymous> (/home/iojs/build/workspace/node-test-commit-linuxone/test/parallel/test-runner-reporters.js:92:14)
20:32:33             ItTest.runInAsyncScope (node:async_hooks:204:9)
20:32:33             ItTest.run (node:internal/test_runner/test:547:25)
20:32:33             ItTest.start (node:internal/test_runner/test:463:17)
20:32:33             node:internal/test_runner/test:796:71
20:32:33             node:internal/per_context/primordials:468:82
20:32:33             new Promise (<anonymous>)
20:32:33             new SafePromise (node:internal/per_context/primordials:436:29)
20:32:33             node:internal/per_context/primordials:468:9
20:32:33             Array.map (<anonymous>)