[Sheriff] Mark */service-worker/target-reloaded-after-crash.js as flaky.

Example failure:
"""
Test that Inspector.targetReloadedAfterCrash is not fired when service worker just created(not restarted)
Started and attached to service_worker target
Stopped service worker and received Inspector.targetCrashed event

FAIL: targetReloadedAfterCrash received for a new service worker
"""

TBR=yurys@chromium.org

Bug: 1046784
Change-Id: I2415e6918957050273640c03e9d6a3b670eb4177
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2519735Reviewed-by: Sahel Sharify <sahel@chromium.org>
Commit-Queue: Sahel Sharify <sahel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824132}

third_party/blink/web_tests/TestExpectations

@@ -5646,7 +5646,7 @@ crbug.com/1046784 http/tests/devtools/bindings/navigator-frame-attach-detach.js
 crbug.com/1046784 http/tests/devtools/forced-layout-in-microtask.js [ Pass Timeout ]
 crbug.com/1046784 http/tests/devtools/application-panel/resources-panel-iframe-idb.js [ Pass Timeout ]
 crbug.com/1046784 http/tests/devtools/a11y-axe-core/sources/scope-pane-a11y-test.js [ Pass Timeout ]
-crbug.com/1046784 http/tests/inspector-protocol/service-worker/target-reloaded-after-crash.js [ Pass Timeout ]
+crbug.com/1046784 http/tests/inspector-protocol/service-worker/target-reloaded-after-crash.js [ Pass Failure Timeout ]
 crbug.com/1046784 http/tests/inspector-protocol/network/navigate-iframe-out2in.js [ Pass Timeout ]
 
 # Sheriff 2020-01-28