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/test/java/org/elasticsearch/xpack/security/profile/ProfileServiceTests.java
}
            final Tuple<String, List<String>> label = hint.getSingleLabel();
            if (label != null) {
                final List<String> labelValues = label.v2();
                assertThat(shouldQueries.remove(0), equalTo(QueryBuilders.termsQuery("user_profile.labels." + label.v1(), labelValues)));
            }
            assertThat(query.minimumShouldMatch(), equalTo("0"));
        } else {
            assertThat(query.should(), empty());
        }
    }
    
    
    
    public void testSecurityProfileOrigin() {
        
        doAnswer(invocation -> {
            assertThat(
                threadPool.getThreadContext().getTransient(ACTION_ORIGIN_TRANSIENT_NAME),
                equalTo(minNodeVersion.onOrAfter(Version.V_8_3_0) ? SECURITY_PROFILE_ORIGIN : SECURITY_ORIGIN)
            );
            @SuppressWarnings("unchecked")
            final ActionListener<MultiSearchResponse> listener = (ActionListener<MultiSearchResponse>) invocation.getArguments()[2];
            listener.onResponse(
                new MultiSearchResponse(
                    new MultiSearchResponse.Item[] {
                        new MultiSearchResponse.Item(SearchResponse.empty(() -> 1L, SearchResponse.Clusters.EMPTY), null) },
                    1L
                )
            );