All sites: Fix icon size in small screen sizes (#37938)

* All sites: Fix icon size in small screen sizes

* changelog

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/9571514856

Upstream-Ref: Automattic/jetpack@c70140f

Author: lupus2k

vendor/automattic/jetpack-mu-wpcom/src/build/wpcom-site-menu/wpcom-site-menu.asset.php

@@ -1 +1 @@
-<?php return array('dependencies' => array(), 'version' => '5bb0c0daba7153ef1b63');
+<?php return array('dependencies' => array(), 'version' => '13199153158cba4ea569');

vendor/automattic/jetpack-mu-wpcom/src/build/wpcom-site-menu/wpcom-site-menu.css

@@ -35,6 +35,7 @@
 		width: 36px;
 		height: 36px;
 		margin: 0 8px;
+		mask-size: cover;
 	}
 }