refactor(2meet-data-optimizer): stop registering the sso group in core

- TMDO_Member_Fields no longer registers user/sso; the definition moved
  unchanged (hash 03543f19) to 2meet-data-optimizer-sso-addon.
- missing_integration_addons(): 2meet-hub-core or 2meet-spoke-sso without
  the SSO AddOn is reported (admin notice + Site Health).
- The deprecated-AddOn notice points hub / spoke users to the SSO AddOn.
- Sites must activate the SSO AddOn before this ships (PR-041); aeav_only
  sites without it fall back to orphan-group restore.
- Verify: core unit 659 / integration 475, SSO 6, HP 142/49, WC 10/22
  green, phpcs clean
- PR: PR-040

tests/unit/DeprecatedAddonsNoticeTest.php

@@ -43,6 +43,17 @@ class DeprecatedAddonsNoticeTest extends TestCase {
 		$this->assertStringContainsString( 'PARTNER-REGISTRATION.md', $html );
 	}
 
+	public function test_hub_and_spoke_point_to_the_sso_addon(): void {
+		$GLOBALS['_wp_options']['active_plugins'] = array( '2meet-data-optimizer-spoke-addon/2meet-data-optimizer-spoke-addon.php' );
+
+		ob_start();
+		TMDO_Deprecated_Addons_Notice::render();
+		$html = (string) ob_get_clean();
+
+		$this->assertStringContainsString( '2meet-data-optimizer-spoke-addon', $html );
+		$this->assertStringContainsString( '2meet-data-optimizer-sso-addon', $html );
+	}
+
 	public function test_no_notice_when_none_active_or_user_cannot_manage(): void {
 		ob_start();
 		TMDO_Deprecated_Addons_Notice::render();