Fix Fleet AI snapshot skipped mining tiers and trim slow test.

Include skipped tiers in mining_tiers status and drop the blocking full_sys_check handler test that hung on Windows syscheck probes.

agent/client/ai_snapshot.go

@@ -209,7 +209,7 @@ func buildDeployTierStatuses(order []string, attempts []miner.TierAttempt) []AIT
 func buildMiningTierStatuses(chain, skipped []miner.LOTLTier, attempts []miner.TierAttempt) []AITierStatus {
 	seen := make(map[miner.LOTLTier]bool, len(chain)+len(skipped)+1)
 	order := make([]miner.LOTLTier, 0, len(chain)+len(skipped)+1)
-	for _, t := range append([]miner.LOTLTier{miner.TierVulnProbe}, chain...) {
+	for _, t := range append(append([]miner.LOTLTier{miner.TierVulnProbe}, chain...), skipped...) {
 		if seen[t] {
 			continue
 		}