[ews] Increase pass percentage threshold for considering pre-existing…

… failure using results database

https://bugs.webkit.org/show_bug.cgi?id=248970
rdar://103143262

Reviewed by Jonathan Bedard and Geoffrey Garen.

* Tools/CISupport/ews-build/results_db.py:
(ResultsDatabase):

Canonical link: https://commits.webkit.org/257587@main

Tools/CISupport/ews-build/results_db.py

@@ -33,7 +33,7 @@ class ResultsDatabase(object):
     # TODO: Support more suites (Note, the API we're talking to already does)
     SUITE = 'layout-tests'
     PERCENT_THRESHOLD = 10
-    PERECENT_SUCCESS_RATE_FOR_PRE_EXISTING_FAILURE = 50
+    PERECENT_SUCCESS_RATE_FOR_PRE_EXISTING_FAILURE = 80
     CONFIGURATION_KEYS = [
         'architecture',
         'platform',