chore(relay): drop speculative removeAllRelays connected-set clear

removeAllRelays() has no call sites — it's dead code — so clearing
_connectedRelays there was never exercised. The live fix for the stale
connected count is the prune in removeRelayInner (driven by updatePool),
which keeps removeAllRelays untouched relative to main.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ukw6FJPFh3JKGXL532p3ae

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip01Core/relay/client/pool/RelayPool.kt

@@ -223,7 +223,6 @@ class RelayPool(
             disconnect()
             relays.clear()
             _availableRelays.update { emptySet() }
-            _connectedRelays.update { emptySet() }
         }
     }