[code coverage] Make iOS coverage builder run on simulators as CQ builder

Set form factors and iOS versions exactly the same as the union of
ios-simulator and ios-simulator-full-configs CQ builders. This is
because a unit test in iOS 12 is failing and we need to gather more
accurate data before running coverage in CQ.

Bug: 1090188
Change-Id: I0875469c874e8745da3f3c1a23d25dbe6297a63d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2258899Reviewed-by: Garrett Beaty <gbeaty@chromium.org>
Commit-Queue: Zhaoyang Li <zhaoyangli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#781452}

testing/buildbot/test_suites.pyl

@@ -5325,34 +5325,34 @@
     'ios_code_coverage_tests': {
       'ios_common_tests': {
         'variants': [
-          'SIM_IPAD_AIR_2_12_4',
-          'SIM_IPAD_AIR_2_13_4',
-          'SIM_IPHONE_X_12_4',
-          'SIM_IPHONE_X_13_4',
+          'SIM_IPHONE_6S_12_4',
+          'SIM_IPHONE_6S_13_4',
         ],
       },
       'ios_eg2_cq_tests': {
         'variants': [
+          'SIM_IPHONE_6S_12_4',
           'SIM_IPAD_AIR_2_12_4',
+          'SIM_IPHONE_6S_13_4',
+          'SIM_IPHONE_7_13_4',
           'SIM_IPAD_AIR_2_13_4',
-          'SIM_IPHONE_X_12_4',
-          'SIM_IPHONE_X_13_4',
         ],
       },
       'ios_eg2_tests': {
         'variants': [
           'SIM_IPAD_AIR_2_12_4',
-          'SIM_IPAD_AIR_2_13_4',
           'SIM_IPHONE_X_12_4',
+          'SIM_IPHONE_7_13_4',
+          'SIM_IPAD_AIR_2_13_4',
           'SIM_IPHONE_X_13_4',
         ],
       },
       'ios_screen_size_dependent_tests': {
         'variants': [
-          'SIM_IPAD_AIR_2_12_4',
-          'SIM_IPAD_AIR_2_13_4',
-          'SIM_IPHONE_X_12_4',
-          'SIM_IPHONE_X_13_4',
+          'SIM_IPHONE_6S_PLUS_13_4',
+          'SIM_IPHONE_6S_13_4',
+          'SIM_IPHONE_SE_13_4',
+          'SIM_IPAD_AIR_2_13_4'
         ],
       },
     },