fix(spark): replace shared spark-events PVC with emptyDir to fix Multi-Attach error

local-path provisioner is RWO-only; attaching a single PVC to master, two
workers, history-server, and streaming pod on separate nodes causes
Multi-Attach errors. Each pod now gets its own ephemeral emptyDir for
/spark-events. Event logging confs removed from CronJobs and streaming
Deployment (logs are pod-local and do not persist across restarts).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

spark-analytics/base/streaming.yaml

@@ -33,10 +33,6 @@ spec:
             - spark.executor.memory=512m
             - --conf
             - spark.driver.memory=512m
-            - --conf
-            - spark.eventLog.enabled=true
-            - --conf
-            - spark.eventLog.dir=/spark-events
             - --class
             - de.nowchess.analytics.LiveDashboardJob
             - local:///app/analytics.jar
@@ -67,12 +63,7 @@ spec:
           volumeMounts:
             - name: spark-checkpoint
               mountPath: /spark-checkpoint
-            - name: spark-events
-              mountPath: /spark-events
       volumes:
         - name: spark-checkpoint
           persistentVolumeClaim:
             claimName: spark-streaming-checkpoint
-        - name: spark-events
-          persistentVolumeClaim:
-            claimName: spark-events