Fix enforcement of unique policy name of policies across spaces (#239631)

Resolves: #228746

Fixes fleet policy name uniqueness not being consistently enforced
across spaces when name or space changes occur:

* When creating an agent policy with packages
(like system), the name incrementation accounts for package names that
already exist in the spaces to be set for the new policy.
* Creating or updating an agent policy for multiple spaces that has the
same name of another policy that is not in the current namespace now
results in an error.
* When an agent policy with multiple spaces has an integration policy
name updated to one that already exists in another space that is not the
current namespace now results in an error.

Author: MichelLosier

x-pack/platform/plugins/shared/fleet/server/routes/agent_policy/handlers.ts

@@ -351,14 +351,10 @@ export const createAgentPolicyHandler: FleetRequestHandler<
   const monitoringEnabled = request.body.monitoring_enabled;
   const logger = appContextService.getLogger().get('httpCreateAgentPolicyHandler');
 
-  const {
-    has_fleet_server: hasFleetServer,
-    force,
-    space_ids: spaceIds,
-    ...newPolicy
-  } = request.body;
+  const { has_fleet_server: hasFleetServer, force, ...newPolicy } = request.body;
   const spaceId = fleetContext.spaceId;
   const authorizationHeader = HTTPAuthorizationHeader.parseFromRequest(request, user?.username);
+  const { space_ids: spaceIds } = request.body;
 
   logger.debug(`Creating agent policy [${newPolicy.name}]`);
 
@@ -401,9 +397,11 @@ export const createAgentPolicyHandler: FleetRequestHandler<
       (spaceIds.length > 1 || (spaceIds.length === 0 && spaceIds[0]) !== spaceId)
     ) {
       await updateAgentPolicySpaces({
-        agentPolicyId: agentPolicy.id,
+        agentPolicy: {
+          ...agentPolicy,
+          space_ids: spaceIds,
+        },
         currentSpaceId: spaceId,
-        newSpaceIds: spaceIds,
         authorizedSpaces,
         options: { force },
       });
@@ -543,8 +541,9 @@ export const updateAgentPolicyHandler: FleetRequestHandler<
   const fleetContext = await context.fleet;
   const esClient = coreContext.elasticsearch.client.asInternalUser;
   const user = appContextService.getSecurityCore().authc.getCurrentUser(request) || undefined;
-  const { force, bumpRevision, space_ids: spaceIds, ...data } = request.body;
+  const { force, bumpRevision, ...data } = request.body;
 
+  const spaceIds = data.space_ids;
   let spaceId = fleetContext.spaceId;
 
   logger.debug(`updating policy [${request.params.agentPolicyId}] in space [${spaceId}]`);
@@ -560,11 +559,10 @@ export const updateAgentPolicyHandler: FleetRequestHandler<
         context
       );
       await updateAgentPolicySpaces({
-        agentPolicyId: request.params.agentPolicyId,
+        agentPolicy: { ...data, id: request.params.agentPolicyId },
         currentSpaceId: spaceId,
-        newSpaceIds: spaceIds,
         authorizedSpaces,
-        options: { force, validateUniqueName: true },
+        options: { force },
       });
 
       spaceId = spaceIds[0];