[terra-functional-testing] Inconsistent IE screenshot dimension

[benbcai]

Story

Description

As a maintainer of terra-functional-testing I want to set and capture the size of the screenshot using the viewport size instead of the window size

Motivation

so that the size of wdio screenshots in IE is consistent and the test can pass when matching against the reference screenshots

Definition of Done

We'll know we're done when screenshots are captured using viewport size and wdio tests can consistently pass when running in IE.

Additional Detail.

The issue is related to #671. We previously updated from viewport size to window size. In terra-functional-testing V2, we decided to revert the change and opted to resolve the issue by increasing the size for the large viewport. It turns out reverting the change still causes sizing issues in IE. We should add back the change made on PR #673.