Survicate tests: inline function stubs, drop fixtures dir

The three fixture files only existed to dodge PHP's "function already
declared" rule across tests. Each stub is now declared inline inside
its test method — namespaced (\WPForTeams\is_wpforteams_site) and
global (has_blog_sticker) stubs both go through an eval'd namespace
block since the test file itself lives in namespace A8C\FSE.
@runInSeparateProcess on each test keeps the function table fresh.

Removes tests/php/features/survicate/fixtures/.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: paulopmt1

projects/packages/jetpack-mu-wpcom/tests/php/features/survicate/Survicate_Test.php

@@ -282,7 +282,9 @@ public function test_should_load_returns_false_on_p2_site_via_wpforteams() {
 			define( 'IS_WPCOM', true );
 		}
 
-		require_once __DIR__ . '/fixtures/wpforteams-stub.php';
+		// Status\Host::is_p2_site() calls \WPForTeams\is_wpforteams_site(); namespaced
+		// functions can't be declared in a method body, so eval a namespace block.
+		eval( 'namespace WPForTeams { function is_wpforteams_site( $blog_id ) { return true; } }' ); // phpcs:ignore Squiz.PHP.Eval.Discouraged,MediaWiki.Usage.ForbiddenFunctions.eval
 
 		$this->set_admin_context();
 		$this->create_and_login_user();
@@ -412,7 +414,9 @@ public function test_get_visitor_traits_returns_is_big_sky_site_false_by_default
 	#[RunInSeparateProcess]
 	#[PreserveGlobalState( false )]
 	public function test_get_visitor_traits_returns_is_big_sky_site_true_for_big_sky_enabled_sticker() {
-		require_once __DIR__ . '/fixtures/big-sky-enabled-sticker-stub.php';
+		// wpcom_has_blog_sticker() in src/utils.php proxies to the global has_blog_sticker().
+		// This file lives in namespace A8C\FSE, so use an eval'd global namespace block.
+		eval( 'namespace { function has_blog_sticker( $sticker, $blog_id ) { return $sticker === "big-sky-enabled"; } }' ); // phpcs:ignore Squiz.PHP.Eval.Discouraged,MediaWiki.Usage.ForbiddenFunctions.eval
 
 		global $pagenow;
 		$pagenow = 'index.php';
@@ -433,7 +437,7 @@ public function test_get_visitor_traits_returns_is_big_sky_site_true_for_big_sky
 	#[RunInSeparateProcess]
 	#[PreserveGlobalState( false )]
 	public function test_get_visitor_traits_returns_is_big_sky_site_true_for_big_sky_free_trial_sticker() {
-		require_once __DIR__ . '/fixtures/big-sky-free-trial-sticker-stub.php';
+		eval( 'namespace { function has_blog_sticker( $sticker, $blog_id ) { return $sticker === "big-sky-free-trial"; } }' ); // phpcs:ignore Squiz.PHP.Eval.Discouraged,MediaWiki.Usage.ForbiddenFunctions.eval
 
 		global $pagenow;
 		$pagenow = 'index.php';