[wpt] Increase timeout multiplier for CCOV builds to 4.

Differential Revision: https://phabricator.services.mozilla.com/D157928

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1792021
gecko-commit: 4ce68ee50da2e00a53f4d9c5cc8d7e95426fd3cb
gecko-reviewers: jgraham
diff --git a/tools/wptrunner/wptrunner/browsers/firefox.py b/tools/wptrunner/wptrunner/browsers/firefox.py
index a69ddd0..c50ce72 100644
--- a/tools/wptrunner/wptrunner/browsers/firefox.py
+++ b/tools/wptrunner/wptrunner/browsers/firefox.py
@@ -63,18 +63,15 @@
             return 4
         else:
             return 2
+    elif run_info_data.get("ccov"):
+        return 4
     elif run_info_data["debug"] or run_info_data.get("asan") or run_info_data.get("tsan"):
-        if run_info_data.get("ccov"):
-            return 4
-        else:
-            return 3
+        return 3
     elif run_info_data["os"] == "android":
         return 4
     # https://bugzilla.mozilla.org/show_bug.cgi?id=1538725
     elif run_info_data["os"] == "win" and run_info_data["processor"] == "aarch64":
         return 4
-    elif run_info_data.get("ccov"):
-        return 2
     return 1