Bug 1564652 [wpt PR 17528] - Update wpt metadata, a=testonly

wpt-pr: 17528
wpt-type: metadata

testing/web-platform/meta/largest-contentful-paint/observe-image.html.ini

@@ -0,0 +1,4 @@
+[observe-image.html]
+  [Element with elementtiming attribute is observable.]
+    expected: FAIL
+