test_lazy_import: add coverage for reload() and sys.modules deletion after reification

Bug report / test coverage gap

Lib/test/test_lazy_import/__init__.py has broad lazy import coverage, but it misses two practical state-transition scenarios after reification:

1. importlib.reload() on a module that was first imported lazily and then reified.
2. Deleting sys.modules[name] after reification and then importing again.

Why this matters

These are common import-state operations and can regress subtly when lazy import behavior changes.
Adding tests helps lock in expected semantics and prevents regressions in future import machinery refactors.

Proposed change

Add two tests in test_lazy_import:

• test_reload_after_lazy_reification_keeps_single_module_object

  • Reify a lazily imported module.
  • Call importlib.reload().
  • Assert identity consistency between the binding and sys.modules[name].

• test_reimport_after_deleting_sys_modules_entry_creates_new_module

  • Reify a lazily imported module.
  • Delete sys.modules[name].
  • Verify old binding still works.
  • Re-import module and assert a new module object is cached.

Affected files

• Lib/test/test_lazy_import/__init__.py

Version

• main (3.15 development branch)

Additional notes

This is test-only; no runtime behavior change is introduced.

Linked PRs

• gh-149014

從 Lib/test/test_lazy_import/init.py 開始，閱讀現有的 lazy-import 覆蓋範圍與相關 helper。先執行 test_lazy_import 測試，然後為 reification 後的 reload() 以及刪除 sys.modules[name] 後的重新匯入新增覆蓋。完成的標準是 binding 與快取的 module 保持所述的 identity 行為，而刪除項目後的重新匯入會建立新的快取 module。