fix(zabbix): bump web probe timeouts 5s→15s + add failureThreshold

zabbix-web nginx+PHP-FPM container serves / at ~3-5s baseline with
occasional 6-7s spikes (probe path renders full dashboard via PHP).
kube-probe was killing the container after 3 consecutive 5s-timeout
499s, producing CrashLoopBackOff alert noise even though the app
was serving real traffic fine.

15s timeout absorbs the natural variance; explicit failureThreshold=3
documents the policy (was implicit default).

Closes the firing PodCrashLoopBackOff (zabbix-web) + pending
HTTPServiceSlow/HTTPServiceDegraded alerts. zabbix.iamworkin.lan
remains slow at the application layer (separate work — PHP-FPM
warm-up + Zabbix server "host not found" agent lookup spam need
their own fixes) but the pod restart loop stops.

apps/zabbix/zabbix.yaml

@@ -305,15 +305,17 @@ spec:
               path: /
               port: 8080
             initialDelaySeconds: 60
-            timeoutSeconds: 5
+            timeoutSeconds: 15
             periodSeconds: 10
+            failureThreshold: 3
           readinessProbe:
             httpGet:
               path: /
               port: 8080
             initialDelaySeconds: 30
             periodSeconds: 5
-            timeoutSeconds: 5
+            timeoutSeconds: 15
+            failureThreshold: 3
 ---
 apiVersion: v1
 kind: Service