Hook into install email

If you see the code, there is no hook to do that. But you can create your own function and remove the part that you don’t need like this

function custom_wp_install( $blog_title, $user_name, $user_email, $public, $deprecated = '', $user_password = '', $language="" ) {
    if ( !empty( $deprecated ) )
        _deprecated_argument( __FUNCTION__, '2.6' );

    wp_check_mysql_version();
    wp_cache_flush();
    make_db_current_silent();
    populate_options();
    populate_roles();

    update_option('blogname', $blog_title);
    update_option('admin_email', $user_email);
    update_option('blog_public', $public);

    if ( $language ) {
        update_option( 'WPLANG', $language );
    }

    $guessurl = wp_guess_url();

    update_option('siteurl', $guessurl);

    // If not a public blog, don't ping.
    if ( ! $public )
        update_option('default_pingback_flag', 0);

    /*
     * Create default user. If the user already exists, the user tables are
     * being shared among blogs. Just set the role in that case.
     */
    $user_id = username_exists($user_name);
    $user_password = trim($user_password);
    $email_password = false;
    if ( !$user_id && empty($user_password) ) {
        $user_password = wp_generate_password( 12, false );
        $message = __('<strong><em>Note that password</em></strong> carefully! It is a <em>random</em> password that was generated just for you.');
        $user_id = wp_create_user($user_name, $user_password, $user_email);
        update_user_option($user_id, 'default_password_nag', true, true);
        $email_password = true;
    } elseif ( ! $user_id ) {
        // Password has been provided
        $message="<em>".__('Your chosen password.').'</em>';
        $user_id = wp_create_user($user_name, $user_password, $user_email);
    } else {
        $message = __('User already exists. Password inherited.');
    }

    $user = new WP_User($user_id);
    $user->set_role('administrator');

    wp_install_defaults($user_id);

    wp_install_maybe_enable_pretty_permalinks();

    flush_rewrite_rules();

    wp_cache_flush();

    /**
     * Fires after a site is fully installed.
     *
     * @since 3.9.0
     *
     * @param WP_User $user The site owner.
     */
    do_action( 'wp_install', $user );

    return array('url' => $guessurl, 'user_id' => $user_id, 'password' => $user_password, 'password_message' => $message);
}