Remove legacy Polymer load benchmarks
The Pica and Topeka load benchmarks are based on the old Polymer 0.5 model
which is not representative of modern Polymer apps. The Pica benchmark is
noisy and fluctuations in its score say more about the device it's running
on than any underlying changes in Chrome code. As for Topeka, that benchmark
has been disabled for six months.
BUG=428207,486144
CQ_EXTRA_TRYBOTS=tryserver.chromium.perf:linux_perf_bisect;tryserver.chromium.perf:mac_perf_bisect;tryserver.chromium.perf:win_perf_bisect;tryserver.chromium.perf:android_nexus5_perf_bisect
Review URL: https://codereview.chromium.org/
1161533006
Cr-Commit-Position: refs/heads/master@{#332475}