RPP: Add VE for long-critical-network-tree

Bug: 372897712
Change-Id: Ic2a2f387f1fa56a11a57abea4d0c49616c40cf91
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6242273
Auto-Submit: Paul Irish <[email protected]>
Commit-Queue: Jack Franklin <[email protected]>
Reviewed-by: Jack Franklin <[email protected]>

Author: paulirish

front_end/ui/visual_logging/KnownContextValues.ts

@@ -3588,6 +3588,7 @@ export const knownContextValues = new Set([
   'timeline.toggle-insight.inp',
   'timeline.toggle-insight.lcp-by-phase',
   'timeline.toggle-insight.lcp-discovery',
+  'timeline.toggle-insight.long-critical-network-tree',
   'timeline.toggle-insight.render-blocking-requests',
   'timeline.toggle-insight.slow-css-selector',
   'timeline.toggle-insight.third-parties',