sheriff: mark page-lifecycle idlharness test timeout under msan

Bug: 1073062
Change-Id: I0f1895ebcf4a6169197ee6bb0b8a8fc05e6748eb
Tbr: collinbaker@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2158972Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#760978}

third_party/blink/web_tests/MSANExpectations

@@ -404,3 +404,6 @@ crbug.com/1047818 [ Linux ] external/wpt/permissions-revoke/idlharness.any.worke
 
 # Sheriff 2020-03-31
 crbug.com/1066647 [ Linux ] http/tests/devtools/sources/debugger-breakpoints/breakpoint-with-sourcemap-dart.js [ Timeout ]
+
+# Sheriff 2020-04-21
+crbug.com/1073062 [ Linux ] external/wpt/page-lifecycle/idlharness.html [ Timeout ]