RPP: fix markers being unclickable

The `width:100%` made it so the first marker in the timeline that was
visible effectively captured every single click event because it ran the
entire width of the canvas.

https://imgur.com/a/wVbsH0x

Removing the width CSS styling doesn't break the markers but ensures
each is clickable.

Bug: 389138443
Change-Id: Iac74604d1db79640d086a81d3cea37cc51a65a5d
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6182304
Commit-Queue: Jack Franklin <[email protected]>
Reviewed-by: Adriana Ixba <[email protected]>

Author: jackfranklin

front_end/panels/timeline/timelineFlameChartView.css

@@ -166,7 +166,6 @@
   position: fixed;
   display: flex;
   bottom: 0;
-  width: 100%;
 }
 
 .overlay-popover span {