[Lighthouse] Change font to match with rest of DevTools

Before: https://i.imgur.com/mzIFQiO.png
After: https://i.imgur.com/d7siraO.png
Bug: none
Change-Id: Ia610daae00cdb5714477dde71a16f3c40c19eed0
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6387323
Reviewed-by: Adam Raine <[email protected]>
Commit-Queue: Kim-Anh Tran <[email protected]>

Author: ktran

front_end/panels/lighthouse/lighthouseStartView.css

@@ -6,8 +6,6 @@
 /* <3 */
 
 .lighthouse-start-view {
-  font-family: Roboto, sans-serif;
-  font-size: var(--font-size);
   line-height: 18px;
   padding: 24px;
   overflow: auto;