As we are rolling out the user profile feature, we'd like to expand the [Usage API](https://www.elastic.co/guide/en/elasticsearch/reference/current/usage-api.html) to report usage stats of user profiles such as (1) number of enabled user profiles and (2) number of user profiles that are [activated](https://www.elastic.co/guide/en/elasticsearch/reference/current/security-api-activate-user-profile.html) over the past X days. 

Response of the Usage API already contains a `security` field that groups relevant stats from security related features. We expect the new stats for user profiles should be added under it as well, for example:
```
{
  "security: {
    "user_profile": {
      "activated": 78,
      "recently_activated": 42  <1>
    }
  }
}
```
<1> The use of `recently_` is chosen to avoid the field to be tied to a specific time period so it is easier to evolve the definition in future.

x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/SecurityUsageTransportAction.java
this.realms = securityServices.realms;
        this.rolesStore = securityServices.rolesStore;
        this.roleMappingStore = securityServices.roleMappingStore;
        this.ipFilter = securityServices.ipFilter;
    }
    @Override
    protected void masterOperation(
        Task task,
        XPackUsageRequest request,
        ClusterState state,
        ActionListener<XPackUsageFeatureResponse> listener
    ) {
        Map<String, Object> sslUsage = sslUsage(settings);
        Map<String, Object> tokenServiceUsage = tokenServiceUsage(settings);
        Map<String, Object> apiKeyServiceUsage = apiKeyServiceUsage(settings);
        Map<String, Object> auditUsage = auditUsage(settings);
        Map<String, Object> ipFilterUsage = ipFilterUsage(ipFilter);
        Map<String, Object> anonymousUsage = singletonMap("enabled", AnonymousUser.isAnonymousEnabled(settings));
        Map<String, Object> fips140Usage = fips140Usage(settings);
        Map<String, Object> operatorPrivilegesUsage = Map.of(
            "available",
            Security.OPERATOR_PRIVILEGES_FEATURE.checkWithoutTracking(licenseState),
            "enabled",
            OperatorPrivileges.OPERATOR_PRIVILEGES_ENABLED.get(settings)
        );
        final AtomicReference<Map<String, Object>> rolesUsageRef = new AtomicReference<>();
        final AtomicReference<Map<String, Object>> roleMappingUsageRef = new AtomicReference<>();
        final AtomicReference<Map<String, Object>> realmsUsageRef = new AtomicReference<>();
        final AtomicReference<Map<String, Object>> domainsUsageRef = new AtomicReference<>();
        final boolean enabled = XPackSettings.SECURITY_ENABLED.get(settings);