[e2e] Bump individual test timeout to 10 seconds

We are landing the timeout increase separatly from enabling the
pool implementation to collect more data for how the windows bots
behave w.r.t. to e2e test stability.

R=jarin@chromium.org

Bug: 1297458
Change-Id: I62d5c6c906031d0ff73adeeed5700fb3cffb391e
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3649881
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Auto-Submit: Simon Zünd <szuend@chromium.org>

test/e2e/.mocharc.js

diff --git a/test/e2e/.mocharc.js b/test/e2e/.mocharc.js
index 56884d1..080014f 100644
--- a/test/e2e/.mocharc.js
+++ b/test/e2e/.mocharc.js
@@ -17,5 +17,9 @@
   extraMochaConfig : {
     // E2E tests are much slower by default than Mocha's 75ms default threshold.
     slow : 1000,
+    // Maintaining pre-allocated frontend tabs in the background while also running
+    // tests can cause very long running tests in some edge cases. We are more linient
+    // in e2e tests.
+    timeout : 10000,
   }
 })