Remove double-up of clear icons from search inputs

What does this MR do and why?

• Browsers add an additional clear icon to type=search fields. This was overlapping with the clear icon we add programatically in input fields.
• I believe this started happening because the code to overwrite this existed in search.scss, but the file was recently removed from global scope and added as a page-specific style (!105818 (diffs)).
• To make it more uniform with other browser overwrites of inputs, I have just added this to forms.scss

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