StepDefinitions.addSeriesToCollection(): remove unused code

[php-coder]

As far I understand, the following code removes a series from user's collection if the series is already belonging to a collection:

mystamps/src/test/java/ru/mystamps/web/tests/StepDefinitions.java

Lines 54 to 58 in f72c87d

	if (driver.findElements(By.id("series-danger")).size() != 0) {
	driver.findElement(By.id("series-danger")).click();
	driver.get(Url.SITE);
	driver.findElement(By.linkText("1 item(s)")).click();
	}

While it was useful during debugging, we don't need it because it's supposed that a test is always running on a clean state (fresh database). I feel that we can remove this code.

Tech debt for f72c87d (#46)

[php-coder]

Won't fix as we're going get rid of Cucumber JVM (#1019).