Remove unused CSS class

[jtquach1]

Describe your changes

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Removed an unused CSS class that was perhaps originally meant to be used for the ETASU button's MUI 5 ListIcon, which only uses words for fontSize and not a numerical pixel value. The ListIcon already uses a fontSize of 'large' and this class isn't used anywhere else.

Issue ticket number and Jira link

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N/A but found while doing https://jira.mitre.org/secure/RapidBoard.jspa?rapidView=4984&projectKey=REMS&view=detail&selectedIssue=REMS-597, while copying over CSS stylesheets from rems-smart-on-fhir

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