Customizer Theme Switcher: Remove "Add New" references.

The current iteration takes you out of the customizer context, which isn't great UX and doesn't really fit into the flows targeted by this particular UI.

fixes #31837.

git-svn-id: https://develop.svn.wordpress.org/trunk@31968 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-customize-section.php

@@ -348,9 +348,6 @@ class WP_Customize_Themes_Section extends WP_Customize_Section {
 			<div class="customize-themes-panel control-panel-content themes-php">
 				<h2><?php esc_html_e( 'Themes' ); ?>
 					<span class="title-count theme-count"><?php echo count( $this->controls ) - 1; ?></span>
-				<?php if ( ! is_multisite() && current_user_can( 'install_themes' ) ) : ?>
-					<a href="<?php echo admin_url( 'theme-install.php' ); ?>" target="_top" class="add-new-h2"><?php echo esc_html_x( 'Add New', 'Add new theme' ); ?></a>
-				<?php endif; ?>
 				</h2>
 				<div class="theme-overlay" tabindex="0" role="dialog" aria-label="<?php esc_attr_e( 'Theme Details' ); ?>"></div>
 				<div id="customize-container"></div>