Feature Hints: disable when plugins cannot be installed on sit… (#14108)

* Feature Hints: disable when plugins cannot be installed on site.

When one cannot install plugins, we do not have to do anything with feature hints.

* Comment new conditional

See #14108 (comment)

modules/plugin-search.php

@@ -1,5 +1,6 @@
 <?php
 
+use Automattic\Jetpack\Constants;
 use Automattic\Jetpack\Tracking;
 
 /**
@@ -15,6 +16,8 @@
 	Jetpack::is_active() &&
 	/** This filter is documented in _inc/lib/admin-pages/class.jetpack-react-page.php */
 	apply_filters( 'jetpack_show_promotions', true ) &&
+	// Disable feature hints when plugins cannot be installed.
+	! Constants::is_true( 'DISALLOW_FILE_MODS' ) &&
 	jetpack_is_psh_active()
 ) {
 	Jetpack_Plugin_Search::init();