fix(ha-test): remove Debian LVM handlers and fix corosync authkey length

- Remove before/after-resync-target LVM handlers (snapshot-resync-target-lvm.sh
  doesn't exist in NixOS; exit code 127 caused DRBD to drop connections on sync)
- Remove split-brain handler pointing to /usr/lib/drbd/ (Debian path)
- Fix testAuthKey from 126 to 128 bytes (corosync minimum is 1024 bits)
- Fix cluster-init.sh quorum check: corosync-quorumtool has no -q flag;
  use -s | grep 'Quorate: Yes' instead

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HaH1cSGvhogRP5ExoF6nD8

test-lab/ha/cluster-init.sh

@@ -39,7 +39,7 @@ die() { echo "[cluster-init] ERROR: $*" >&2; exit 1; }
 # ── 1. Wait for corosync quorum ──────────────────────────────────────────
 log "Waiting for corosync quorum..."
 for i in $(seq 1 30); do
-  if corosync-quorumtool -q &>/dev/null; then
+  if corosync-quorumtool -s 2>/dev/null | grep -q 'Quorate:.*Yes'; then
     log "Quorum established"
     break
   fi