feat: drop the ASGI send/receive spans from traces

[lesnik512]

Sets opentelemetry_exclude_spans=["receive", "send"] in api_bootstrapper_config. lite-bootstrap passes it to FastAPIInstrumentor.instrument_app (lite-bootstrap #225, available since 1.8.0; the template is on 1.9.3).

Why

A traced GET /api/decks/{id}/ records 6 spans: the server span, 2 http send spans, connect and 2 SELECT. The two send spans mark when the response start and body went out, which is rarely worth looking at for a JSON API. Dropping them is cheap. The benchmark below is the same harness as #85: the full app driven through raw ASGI, with the OTLP exporter encoding spans and then dropping them. Medians of 3 runs, in req/s:

	1 client	100 clients
no tracing	1450	1411
always on	836	858
always on, send/receive excluded	876	923
10% ratio sampler	1116	1058
10% ratio sampler, send/receive excluded	1142	1093

The README notes the setting and says to remove it if those spans are needed.

Tests

test_request_has_no_asgi_event_spans sends a real GET /api/decks/ and asserts that, apart from SQLAlchemy spans, the only span recorded is the SERVER span. It failed before the settings change, when INTERNAL event spans were present.

litestar-sqlalchemy-template will get the same change once lite-bootstrap releases modern-python/lite-bootstrap#288.