gpu: Mark maps pixel test as flaky on Nexus 5

Bug: 1009137
Change-Id: Ie3dcfd7dd30e63091573a2c4cbb50ee92a2494d3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1829250
Auto-Submit: Sunny Sachanandani <sunnyps@chromium.org>
Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Commit-Queue: Sunny Sachanandani <sunnyps@chromium.org>
Cr-Commit-Position: refs/heads/master@{#700945}

content/test/gpu/gpu_tests/test_expectations/maps_expectations.txt

 # tags: [ android ]
-# tags: [ android-nexus-5x ]
-# tags: [ skia-renderer ]
+# tags: [ android-nexus-5x android-nexus-5 ]
+# tags: [ skia-renderer no-skia-renderer ]
 # results: [ Failure RetryOnFailure Skip ]
 
 crbug.com/1006045 [ android android-nexus-5x skia-renderer ] Maps_maps [ Failure ]
+crbug.com/1009137 [ android android-nexus-5 no-skia-renderer ] Maps_maps [ RetryOnFailure ]