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/profile/ProfileService.java
);
            }, updateException -> {
                
                
                if (ExceptionsHelper.unwrapCause(updateException) instanceof VersionConflictEngineException) {
                    getVersionedDocument(currentVersionedDocumentBySearch.doc.uid(), ActionListener.wrap(versionedDocumentByGet -> {
                        if (shouldSkipUpdateForActivate(versionedDocumentByGet.doc, newProfileDocument)) {
                            logger.debug(
                                "suppress version conflict for activate update because last_synchronized [{}] is within grace period",
                                versionedDocumentByGet.doc.lastSynchronized()
                            );
                            listener.onResponse(versionedDocumentByGet.toProfile(Set.of()));
                        } else {
                            listener.onFailure(updateException);
                        }
                    }, getException -> {
                        getException.addSuppressed(updateException);
                        listener.onFailure(getException);
                    }));
                } else {
                    listener.onFailure(updateException);
                }
            })
        );
    }
    
    
    boolean shouldSkipUpdateForActivate(ProfileDocument currentProfileDocument, ProfileDocument newProfileDocument) {
        assert newProfileDocument.enabled() : "new profile document must be enabled";
        if (newProfileDocument.user().equals(currentProfileDocument.user())