Drives the real imported-before-installed transition: seeds a fake SDK
into sys.modules, resets the adapter globals to the placeholder the
fallback block leaves behind, stubs the installer to a no-op, then calls
check_telegram_requirements() and asserts no placeholder survived.
Asserting over the whole stubbed set rather than one name means the next
symbol dropped from the rebind list fails here too, naming itself:
AssertionError: lazy install left these bound to the import-time
placeholder: ['TypeHandler']
Originally written by Tair Asim in #85607, which was closed as a
duplicate of this PR. Moved into its own file to match the convention
already used by test_discord_lazy_install_views.py and
test_feishu_lazy_import.py, and widened from three hard-coded symbol
checks to the full set.
Co-authored-by: Pavel Lesyuk <paul.lesyuk@gmail.com>
134bf66b3b