Revert "target latest bokken images on yamato"

This reverts commit 210eaa1.

Author: LPLafontaineB

.yamato/mobile-build-and-run.yml

@@ -9,7 +9,7 @@ Build_Player_With_Tests_iOS_{{ project.name }}_{{ editor }}:
     name: build {{ project.name }} - {{ editor }} on iOS
     agent:
         type: Unity::VM::osx
-        image: mobile/macos-10.15-testing:latest
+        image: mobile/macos-10.15-testing:stable
         flavor: b1.large
 
     commands:
@@ -37,7 +37,7 @@ Build_Player_With_Tests_Android_{{ project.name }}_{{ editor }}:
         type: Unity::VM
         # Any generic image can be used, no need to have Android tools in the image for building
         # All Android tools will be downloaded by unity-downloader-cli
-        image: desktop/android-execution-r19:latest
+        image: desktop/android-execution-r19:v0.1.1-860408
         flavor: b1.xlarge
 
     commands:
@@ -103,7 +103,7 @@ mobile_test_android_{{ project.name }}_{{ editor }}:
     name: {{ project.name }} mobile project tests - {{ editor }} on Android
     agent:
         type: Unity::mobile::shield
-        image: mobile/android-execution-r19:latest
+        image: mobile/android-execution-r19:stable
         flavor: b1.medium
 
     # Skip repository cloning