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
profileService.doUpdate(mock(UpdateRequest.class), future2);
        final RuntimeException e2 = expectThrows(RuntimeException.class, future2::actionGet);
        assertThat(e2, is(expectedException));
        
        doAnswer(invocation -> {
            assertThat(
                threadPool.getThreadContext().getTransient(ACTION_ORIGIN_TRANSIENT_NAME),
                equalTo(minNodeVersion.onOrAfter(Version.V_8_3_0) ? SECURITY_PROFILE_ORIGIN : SECURITY_ORIGIN)
            );
            final ActionListener<?> listener = (ActionListener<?>) invocation.getArguments()[2];
            listener.onFailure(expectedException);
            return null;
        }).when(client).execute(eq(SearchAction.INSTANCE), any(SearchRequest.class), anyActionListener());
        final PlainActionFuture<SuggestProfilesResponse> future3 = new PlainActionFuture<>();
        profileService.suggestProfile(
            new SuggestProfilesRequest(Set.of(), "", 1, null),
            new TaskId(randomAlphaOfLength(20), randomNonNegativeLong()),
            future3
        );
        final RuntimeException e3 = expectThrows(RuntimeException.class, future3::actionGet);
        assertThat(e3, is(expectedException));
    }
    public void testActivateProfileWithDifferentUidFormats() throws IOException {
        final ProfileService service = spy(
            new ProfileService(Settings.EMPTY, Clock.systemUTC(), client, profileIndex, mock(ClusterService.class), domainName -> {
                if (domainName.startsWith("hash")) {
                    return new DomainConfig(domainName, Set.of(), false, null);
                } else {
                    return new DomainConfig(domainName, Set.of(), true, "suffix");
                }