Edit Agent manifest to mount node's /etc directory. (#143492)

Corresponding change made in Agent repository with:
https://github.com/elastic/elastic-agent/pull/1382

Co-authored-by: Yash Tewari <yash.tewari@elastic.co>
Co-authored-by: Oren Zohar <85433724+oren-zohar@users.noreply.github.com>

x-pack/plugins/fleet/server/services/elastic_agent_manifest.ts

@@ -81,21 +81,12 @@ spec:
             - name: varlog
               mountPath: /var/log
               readOnly: true
-            - name: etc-kubernetes
-              mountPath: /hostfs/etc/kubernetes
+            - name: etc-full
+              mountPath: /hostfs/etc
               readOnly: true
             - name: var-lib
               mountPath: /hostfs/var/lib
               readOnly: true
-            - name: passwd
-              mountPath: /hostfs/etc/passwd
-              readOnly: true
-            - name: group
-              mountPath: /hostfs/etc/group
-              readOnly: true
-            - name: etcsysmd
-              mountPath: /hostfs/etc/systemd
-              readOnly: true
       volumes:
         - name: datastreams
           configMap:
@@ -113,26 +104,15 @@ spec:
         - name: varlog
           hostPath:
             path: /var/log
-        # Needed for cloudbeat
-        - name: etc-kubernetes
+        # The following volumes are needed for Cloud Security Posture integration (cloudbeat)
+        # If you are not using this integration, then these volumes and the corresponding
+        # mounts can be removed.
+        - name: etc-full
           hostPath:
-            path: /etc/kubernetes
-        # Needed for cloudbeat
+            path: /etc
         - name: var-lib
           hostPath:
             path: /var/lib
-        # Needed for cloudbeat
-        - name: passwd
-          hostPath:
-            path: /etc/passwd
-        # Needed for cloudbeat
-        - name: group
-          hostPath:
-            path: /etc/group
-        # Needed for cloudbeat
-        - name: etcsysmd
-          hostPath:
-            path: /etc/systemd
 ---
 apiVersion: rbac.authorization.k8s.io/v1
 kind: ClusterRoleBinding
@@ -367,21 +347,12 @@ spec:
             - name: varlog
               mountPath: /var/log
               readOnly: true
-            - name: etc-kubernetes
-              mountPath: /hostfs/etc/kubernetes
+            - name: etc-full
+              mountPath: /hostfs/etc
               readOnly: true
             - name: var-lib
               mountPath: /hostfs/var/lib
               readOnly: true
-            - name: passwd
-              mountPath: /hostfs/etc/passwd
-              readOnly: true
-            - name: group
-              mountPath: /hostfs/etc/group
-              readOnly: true
-            - name: etcsysmd
-              mountPath: /hostfs/etc/systemd
-              readOnly: true
             - name: etc-mid
               mountPath: /etc/machine-id
               readOnly: true
@@ -398,26 +369,15 @@ spec:
         - name: varlog
           hostPath:
             path: /var/log
-        # Needed for cloudbeat
-        - name: etc-kubernetes
+        # The following volumes are needed for Cloud Security Posture integration (cloudbeat)
+        # If you are not using this integration, then these volumes and the corresponding
+        # mounts can be removed.
+        - name: etc-full
           hostPath:
-            path: /etc/kubernetes
-        # Needed for cloudbeat
+            path: /etc
         - name: var-lib
           hostPath:
             path: /var/lib
-        # Needed for cloudbeat
-        - name: passwd
-          hostPath:
-            path: /etc/passwd
-        # Needed for cloudbeat
-        - name: group
-          hostPath:
-            path: /etc/group
-        # Needed for cloudbeat
-        - name: etcsysmd
-          hostPath:
-            path: /etc/systemd
         # Mount /etc/machine-id from the host to determine host ID
         # Needed for Elastic Security integration
         - name: etc-mid