chore: reduce log noise for high-throughput blocks (#3229)

## Summary

Reduces INFO-level log noise in production when running with 60-100
transactions per block.

### Changes

| File | Change |
|---|---|
| `crates/services/importer/src/importer.rs` | Replace full `tx_status`
receipt traces in span with `tx_count`; full details moved to TRACE |
| `crates/services/p2p/src/service.rs` | "Received gossip message" INFO
→ DEBUG (per-message) |
| `crates/services/sync/src/state.rs` | "Status change from" INFO →
DEBUG (per-block during sync) |
| `crates/fuel-core/src/service/adapters/graphql_api.rs` | "Transaction
successfully included in block" INFO → DEBUG (per-tx) |
| `crates/services/txpool_v2/src/pool/collisions.rs` | Collision logs
kept at INFO |

### Impact

In a representative production log sample (~2000 lines), ~86% of lines
came from these sources. After this change, INFO output is limited to
startup messages, periodic service events, committed block summaries
(with tx count), and collision events.

Full receipt traces and per-transaction details remain accessible at
DEBUG/TRACE level.