Remove unnecessary attributes from default rendered state integration test

[juwara0]

These can be removed from the default rendered test:

sl-ember-components/tests/integration/components/sl-date-range-picker-test.js

Lines 17 to 19 in 7c84149

	label="Select date range"
	startDatePlaceholder="__StartPlaceholder__"
	endDatePlaceholder="__EndPlaceholder__"