WS2-1644: fix(unity-bootstrap-theme): set a max-width on donut chart text

[bebaps]

Description

Currently, the text on Donut charts can expand beyond the chart width and is hidden underneath when doing so. This PR adds a simple max-width on Donut Chart text to remain visible.

Links

• JIRA ticket

Checklist

• [x] Unity project successfully builds from root yarn install & yarn build
• [x] Commits do not contain multiple scopes
• [x] No new console errors

Browsers

• [x] Chrome
• [x] Safari
• [x] Firefox