Recover stuck multistream head and cap lower bound retries

[tonatoz]

Problem

On Linea (linea-besu), Dshackle stops updating the multistream head until restart:

No head updates Multistream of LINEA for 349826761 ms @ DynamicMergedHead
There are too much retries to calculate 16024083 lower bound of upstream PROOF, block Lineanodeeu probably this error with message `Worldstate unavailable` is not retryable

These are two independent bugs.

1. Multistream head freezes

PriorityForkChoice accepts only height > current and never resets. AbstractHead.onNoHeadUpdates() was a no-op. If an upstream height ever drops below the max the multistream has seen (node rollback/resync, or one bogus high block), the head stays frozen until the node passes the old max.

Fix: ForkChoice.reset() (default no-op). PriorityForkChoice.reset() lets the next unseen block through regardless of height, without clearing the current head. AbstractHead.onNoHeadUpdates() calls forkChoice.reset() (after 60s without updates).

2. PROOF lower bound retries forever

Besu returns World state unavailable for eth_getProof on pruned state. It was not in NO_PROOF_ERRORS, and RecursiveLowerBound.retrySpec used Long.MAX_VALUE retries, so the detector never settled.

Fix: add World state unavailable / Worldstate unavailable to NO_PROOF_ERRORS; cap retries at 30 (a block then counts as "no data"); warn once on the last retry; fix swapped log arguments (type, upstreamId, block).

Supersedes #904 (it covers only one spelling and keeps unlimited retries).

Build

grpcVersion 1.49.2 → 1.81.0 (matches grpc runtime; 1.49.2 plugin is x86_64-only and fails on arm64 without Rosetta).

Tests

• PriorityForkChoiceSpec: lower block accepted once after reset().
• RecursiveLowerBoundServiceTest: PROOF bound settles for both Besu messages and for an unknown error (fails on old code).
• ./gradlew check: all pass except IntegrationTest (needs Docker, unrelated).