[EWS] Status bubble tooltip might display success message sometimes on a failed build if the last step in the build succeeds. For the failed builds, status bubble tooltip displays the message from the last step. If the last step is successful (but some other step failed), it might be misleading. e.g.: https://ews-build.webkit.org/#/builders/20/builds/11444
Created attachment 387715 [details] Patch
Tested in https://ews.webkit-uat.org/status-bubble/387402/
Committed r254545: <https://trac.webkit.org/changeset/254545>
<rdar://problem/58588995>