[Stack Monitoring] update read_exceptions mappings (#94875)

* update read_exceptions mappings

* align with legacy mappings

---------

Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>

x-pack/plugin/core/src/main/resources/monitoring-es-mb.json

@@ -2042,7 +2042,26 @@
                   "type": "keyword"
                 },
                 "read_exceptions": {
-                  "type": "nested"
+                  "type": "nested",
+                  "properties": {
+                    "from_seq_no": {
+                      "type": "long"
+                    },
+                    "retries": {
+                      "type": "integer"
+                    },
+                    "exception": {
+                      "type": "object",
+                      "properties": {
+                        "type" : {
+                          "type": "keyword"
+                        },
+                        "reason": {
+                          "type": "text"
+                        }
+                      }
+                    }
+                  }
                 },
                 "shard_id": {
                   "type": "long"

x-pack/plugin/monitoring/src/main/java/org/elasticsearch/xpack/monitoring/MonitoringTemplateRegistry.java

@@ -78,7 +78,7 @@ public class MonitoringTemplateRegistry extends IndexTemplateRegistry {
      * writes monitoring data in ECS format as of 8.0. These templates define the ECS schema as well as alias fields for the old monitoring
      * mappings that point to the corresponding ECS fields.
      */
-    public static final int STACK_MONITORING_REGISTRY_VERSION = Version.V_8_0_0.id + 7;
+    public static final int STACK_MONITORING_REGISTRY_VERSION = Version.V_8_0_0.id + 8;
     private static final String STACK_MONITORING_REGISTRY_VERSION_VARIABLE = "xpack.stack.monitoring.template.release.version";
     private static final String STACK_TEMPLATE_VERSION = "8";
     private static final String STACK_TEMPLATE_VERSION_VARIABLE = "xpack.stack.monitoring.template.version";