fix: Provide accurate instance stats for active user count (#29327)

Fixes https://github.com/appsmithorg/cloud-services/issues/1457
EE PR: https://github.com/appsmithorg/appsmith-ee/pull/3033

## Summary by CodeRabbit

- **New Features**
- Introduced a new indicator to distinguish system-generated users from
regular users.

- **Enhancements**
- Improved user count accuracy by excluding system-generated users from
active user statistics.

- **Database Changes**
- Executed a migration to mark existing anonymous users as
system-generated.

- **Bug Fixes**
- Adjusted user repository queries to correctly count
non-system-generated users.

app/server/appsmith-server/src/main/java/com/appsmith/server/domains/User.java

@@ -110,6 +110,12 @@ public class User extends BaseDomain implements UserDetails, OidcUser {
     @JsonView(Views.Public.class)
     private String tenantId;
 
+    // Field to indicate if the user is system generated or not. Expected to be `true` for system generated users, null
+    // otherwise.
+    // e.g. AnonymousUser is created by the system migration during the first time startup.
+    @JsonView(Views.Internal.class)
+    Boolean isSystemGenerated;
+
     // TODO: Populate these attributes for a user. Generally required for OAuth2 logins
     @Override
     @JsonView(Views.Public.class)

app/server/appsmith-server/src/main/java/com/appsmith/server/migrations/db/ce/Migration037MarkAnonymousUserAsSystemGenerated.java

@@ -0,0 +1,43 @@
+package com.appsmith.server.migrations.db.ce;
+
+import com.appsmith.server.domains.QUser;
+import com.appsmith.server.domains.User;
+import com.mongodb.client.result.UpdateResult;
+import io.mongock.api.annotations.ChangeUnit;
+import io.mongock.api.annotations.Execution;
+import io.mongock.api.annotations.RollbackExecution;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.data.mongodb.core.MongoTemplate;
+import org.springframework.data.mongodb.core.query.Update;
+
+import static com.appsmith.server.repositories.ce.BaseAppsmithRepositoryCEImpl.fieldName;
+import static org.springframework.data.mongodb.core.query.Criteria.where;
+import static org.springframework.data.mongodb.core.query.Query.query;
+
+@Slf4j
+@ChangeUnit(order = "037", id = "mark-anonymous-user-as-system-generated", author = " ")
+public class Migration037MarkAnonymousUserAsSystemGenerated {
+    private final MongoTemplate mongoTemplate;
+
+    public Migration037MarkAnonymousUserAsSystemGenerated(MongoTemplate mongoTemplate) {
+        this.mongoTemplate = mongoTemplate;
+    }
+
+    @RollbackExecution
+    public void rollbackExecution() {}
+
+    @Execution
+    public void executeMigration() {
+
+        final Update update = new Update();
+        update.set(fieldName(QUser.user.isSystemGenerated), true);
+        try {
+            // We expect only 1 anonymous user to be present in the system, but we are using updateMulti to be safe.
+            UpdateResult result = mongoTemplate.updateMulti(
+                    query(where(fieldName(QUser.user.isAnonymous)).is(true)), update, User.class);
+            log.info("Marked {} anonymous users as system generated", result.getModifiedCount());
+        } catch (Exception e) {
+            log.error("Error while marking anonymous user as system generated", e);
+        }
+    }
+}

app/server/appsmith-server/src/main/java/com/appsmith/server/repositories/ce/UserRepositoryCE.java

@@ -11,7 +11,14 @@ public interface UserRepositoryCE extends BaseRepository<User, String>, CustomUs
 
     Mono<User> findByCaseInsensitiveEmail(String email);
 
-    Mono<Long> countByDeletedAtNull();
+    /**
+     * This method returns the count of all users that are not deleted and are not system generated.
+     *
+     * @param excludeSystemGenerated If true, then the count of all users that are not deleted and are not system
+     *                               generated is returned.
+     * @return  The count of all users that are not deleted and are not system generated.
+     */
+    Mono<Long> countByDeletedAtIsNullAndIsSystemGeneratedIsNot(Boolean excludeSystemGenerated);
 
     Mono<User> findByEmailAndTenantId(String email, String tenantId);
 }

app/server/appsmith-server/src/main/java/com/appsmith/server/solutions/ce/PingScheduledTaskCEImpl.java

@@ -122,13 +122,19 @@ public class PingScheduledTaskCEImpl implements PingScheduledTaskCE {
         }
 
         Mono<String> publicPermissionGroupIdMono = permissionGroupService.getPublicPermissionGroupId();
+
+        // Get the non-system generated active user count
+        Mono<Long> userCountMono = userRepository
+                .countByDeletedAtIsNullAndIsSystemGeneratedIsNot(true)
+                .defaultIfEmpty(0L);
+
         Mono<Tuple6<Long, Long, Long, Long, Long, Long>> nonDeletedObjectsCountMono = Mono.zip(
                 workspaceRepository.countByDeletedAtNull().defaultIfEmpty(0L),
                 applicationRepository.countByDeletedAtNull().defaultIfEmpty(0L),
                 newPageRepository.countByDeletedAtNull().defaultIfEmpty(0L),
                 newActionRepository.countByDeletedAtNull().defaultIfEmpty(0L),
                 datasourceRepository.countByDeletedAtNull().defaultIfEmpty(0L),
-                userRepository.countByDeletedAtNull().defaultIfEmpty(0L));
+                userCountMono);
 
         publicPermissionGroupIdMono
                 .flatMap(publicPermissionGroupId -> Mono.zip(