Raise the base litestar floor to 2.22 and delete the plugin probe #331

Split from #315. The base litestar extra is >=2.19; only litestar-otl needs 2.22 (pyproject.toml), because litestar.plugins.opentelemetry first appears in 2.22.0. That split is why is_litestar_opentelemetry_installed probes litestar.plugins.opentelemetry (lite_bootstrap/import_checker.py:33-38) and why the skip message says "or litestar>=2.22 is not installed" (lite_bootstrap/bootstrappers/litestar_bootstrapper.py:213). The probe is also one of the dotted find_spec calls that import litestar when lite_bootstrap is imported (see #308).

Work

• Raise the base litestar floor to 2.22, and delete the litestar>=2.22 line and its comment from litestar-otl.
• Delete the litestar.plugins.opentelemetry probe from is_litestar_opentelemetry_installed and the "or litestar>=2.22" part of missing_dependency_message. No test asserts that message today.
• No behaviour changes at the new floor, so no new failing test. The existing suite and the floors job are the gate.

Verify: the floors job in .github/workflows/_checks.yml passes for the litestar target. Run its steps locally before pushing, as AGENTS.md:27-29 asks.

Breaking for anyone pinned below litestar 2.22, released on 2026-05-20: their resolver cannot install 2.0.