Add EarlGrey tests tryjobs to ios changes.  We want to have EG
tests running for at least ios changes to reduce tree breakages.

Since the ios-simulator-full-configs has only 8 builders, iOS CLs might
experience extra landing time due to the tryjob size and limited capacity.

Bug: 782735
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I8c00dbe1963893af19c37d7410e6d57c8d37ab5d
Reviewed-on: https://chromium-review.googlesource.com/759166


Reviewed-by: Rohit Rao (ping after 24h) <rohitrao@chromium.org>
Commit-Queue: Menglu Huang <huangml@chromium.org>
Cr-Commit-Position: refs/heads/master@{#515214}