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/qa/profile/src/javaRestTest/java/org/elasticsearch/xpack/security/profile/ProfileIT.java
final Response getUserResponse = adminClient().performRequest(getUserRequest);
        assertOK(getUserResponse);
        responseAsMap(getUserResponse).forEach((k, v) -> {
            if (username.equals(k)) {
                assertThat(castToMap(v).get("profile_uid"), equalTo(profile.get("uid")));
            } else {
                assertThat(castToMap(v), not(hasKey("profile_uid")));
            }
        });
    }
    private Map<String, Object> doActivateProfile() throws IOException {
        return doActivateProfile("rac-user", "x-pack-test-password");
    }
    private Map<String, Object> doActivateProfile(String username, String password) throws IOException {
        final Request activateProfileRequest = new Request("POST", "_security/profile/_activate");
        activateProfileRequest.setJsonEntity("""
            {
              "grant_type": "password",
              "username": "%s",
              "password": "%s"
            }""".formatted(username, password));
        final Response activateProfileResponse = adminClient().performRequest(activateProfileRequest);
        assertOK(activateProfileResponse);
        return responseAsMap(activateProfileResponse);
    }
    private Map<String, Object> doGetProfile(String uid) throws IOException {
        return doGetProfile(uid, null);
    }
    private Map<String, Object> doGetProfile(String uid, @Nullable String dataKey) throws IOException {
        final Map<String, Object> responseMap = doGetProfiles(List.of(uid), dataKey);