Test: Replace 'I should see "..." style "..." value "..."' Behat step in smart menus

[abias]

This is a follow-up issue to #300

The smart menu patch shipped with a new Behat test step I should see "..." style "..." value "..."

This step is just used once in a scenario on https://github.com/moodle-an-hochschulen/moodle-theme_boost_union/blob/f5d593275c6ec4e8d2e446e3f82a51823e2f6e87/tests/behat/theme_boost_union_menusettings_application.feature#L213C70-L213C73

According to my understanding, this step does more or less the same

moodle-theme_boost_union/tests/behat/behat_theme_boost_union_behat_smartmenus.php

Lines 97 to 121 in f5d5932

	/**
	* Verify the card size height.
	*
	* @Given /^I should see "(?P<element>(?:[^"]|\\")*)" style "(?P<rule>(?:[^"]|\\")*)" value "(?P<value>(?:[^"]|\\")*)"$/
	* @param string $selector
	* @param string $rule
	* @param string $value
	*/
	public function i_should_see_style_value($selector, $rule, $value) {
	// The DOM and the JS should be all ready and loaded. Running without spinning
	// as this is a widely used step and we can not spend time here trying to see
	// a DOM node that is not always there (at the moment clean is not even the
	// default theme...).
	$navbuttonjs = "return (
	Y.one('$selector') &&
	Y.one('$selector').getComputedStyle('$rule') !== $value
	)";
	// Adding an extra click we need to show the 'Log in' link.
	if (!$this->evaluate_script($navbuttonjs)) {
	return false;
	}
	return true;
	}

what the custom DOM element ... should have computed style ... ... step which exists in Boost Union already does.

It would be worthwhile to get rid of this duplicated step and just use one step for the same purpose.

[abias]

This was solved some time ago by #501