[resultdb][iOS] enable ResultDB on all iOS builders with "enable_resultdb"

To stop using result_adapter since iOS runner should be able to report results directly.

Bug: 1136998
Change-Id: I0686ff23a16d5a59ddae1b80cf5b21df4240bf61
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2561462
Commit-Queue: Chan Li <chanli@chromium.org>
Reviewed-by: Stephen Martinis <martiniss@chromium.org>
Cr-Commit-Position: refs/heads/master@{#833153}

testing/buildbot/waterfalls.pyl

@@ -1749,6 +1749,7 @@
           'all'
         ],
         'mixins': [
+          'enable_resultdb',
           'mac_10.15',
           'mac_toolchain',
           'out_dir_arg',
@@ -1780,6 +1781,7 @@
           'url_unittests'
         ],
         'mixins': [
+          'enable_resultdb',
           'ios_restart_device',
           'limited_capacity_bot',
           'mac_10.15',
@@ -2428,6 +2430,7 @@
       },
       'ios-asan': {
         'mixins': [
+          'enable_resultdb',
           'mac_10.15',
           'mac_toolchain',
           'out_dir_arg',
@@ -2440,6 +2443,7 @@
       },
       'ios-simulator-code-coverage': {
         'mixins': [
+          'enable_resultdb',
           'ios_output_disabled_tests',
           'isolate_profile_data',
           'mac_10.15',
@@ -2454,6 +2458,7 @@
       },
       'ios-simulator-coverage-exp': {
         'mixins': [
+          'enable_resultdb',
           'isolate_profile_data',
           'mac_10.15',
           'mac_toolchain',
@@ -2467,6 +2472,7 @@
       },
       'ios-simulator-cronet': {
         'mixins': [
+          'enable_resultdb',
           'mac_10.15',
           'mac_toolchain',
           'out_dir_arg',
@@ -2479,6 +2485,7 @@
       },
       'ios-simulator-full-configs-coverage-exp': {
         'mixins': [
+          'enable_resultdb',
           'isolate_profile_data',
           'mac_10.15',
           'mac_toolchain',
@@ -2492,6 +2499,7 @@
       },
       'ios-simulator-multi-window': {
         'mixins': [
+          'enable_resultdb',
           'mac_10.15',
           'mac_toolchain',
           'out_dir_arg',
@@ -2504,6 +2512,7 @@
       },
       'ios-webkit-tot': {
         'mixins': [
+          'enable_resultdb',
           'ios_custom_webkit',
           'mac_10.15',
           'mac_toolchain',
@@ -2537,6 +2546,7 @@
           'all',
         ],
         'mixins': [
+          'enable_resultdb',
           'mac_10.15',
           'mac_toolchain',
           'out_dir_arg',
@@ -2554,6 +2564,7 @@
           'all',
         ],
         'mixins': [
+          'enable_resultdb',
           'mac_10.15',
           'mac_toolchain',
           'out_dir_arg',
@@ -4892,6 +4903,7 @@
           'all',
         ],
         'mixins': [
+          'enable_resultdb',
           'isolate_profile_data',
           'mac_10.15',
           'mac_toolchain',
@@ -4908,6 +4920,7 @@
           'all'
         ],
         'mixins': [
+          'enable_resultdb',
           'isolate_profile_data',
           'mac_10.15',
           'mac_toolchain',
@@ -4924,6 +4937,7 @@
           'all'
         ],
         'mixins': [
+          'enable_resultdb',
           'mac_10.15',
           'mac_toolchain',
           'out_dir_arg',