[Open Screen] Convert openscreen builders to Python3.

Bug: 1256430
Change-Id: I20cda66778e6ac7775a0e7ed4fc7cd2387ba087c
Reviewed-on: https://chromium-review.googlesource.com/c/openscreen/+/3485321
Reviewed-by: Jordan Bayles <jophba@chromium.org>
diff --git a/infra/config/global/generated/cr-buildbucket.cfg b/infra/config/global/generated/cr-buildbucket.cfg
index f6ad01a..866cb62 100644
--- a/infra/config/global/generated/cr-buildbucket.cfg
+++ b/infra/config/global/generated/cr-buildbucket.cfg
@@ -124,6 +124,10 @@
         '  "target_cpu": "x64"'
         '}'
       service_account: "openscreen-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
     }
     builders {
       name: "linux64_coverage_debug"
@@ -156,6 +160,10 @@
         '  "use_coverage": true'
         '}'
       service_account: "openscreen-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
     }
     builders {
       name: "linux64_debug"
@@ -188,6 +196,10 @@
         '  "target_cpu": "x64"'
         '}'
       service_account: "openscreen-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
     }
     builders {
       name: "linux64_gcc_debug"
@@ -216,6 +228,10 @@
         '  "use_goma": false'
         '}'
       service_account: "openscreen-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
     }
     builders {
       name: "linux64_tsan"
@@ -247,6 +263,10 @@
         '  "target_cpu": "x64"'
         '}'
       service_account: "openscreen-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
     }
     builders {
       name: "linux_arm64_debug"
@@ -279,6 +299,10 @@
         '  "target_cpu": "arm64"'
         '}'
       service_account: "openscreen-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
     }
     builders {
       name: "mac_debug"
@@ -313,6 +337,10 @@
         path: "osx_sdk"
       }
       service_account: "openscreen-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
     }
   }
 }
@@ -437,6 +465,10 @@
         '  "target_cpu": "x64"'
         '}'
       service_account: "openscreen-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
     }
     builders {
       name: "linux64_coverage_debug"
@@ -468,6 +500,10 @@
         '  "use_coverage": true'
         '}'
       service_account: "openscreen-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
     }
     builders {
       name: "linux64_debug"
@@ -499,6 +535,10 @@
         '  "target_cpu": "x64"'
         '}'
       service_account: "openscreen-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
     }
     builders {
       name: "linux64_gcc_debug"
@@ -526,6 +566,10 @@
         '  "use_goma": false'
         '}'
       service_account: "openscreen-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
     }
     builders {
       name: "linux64_tsan"
@@ -556,6 +600,10 @@
         '  "target_cpu": "x64"'
         '}'
       service_account: "openscreen-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
     }
     builders {
       name: "linux_arm64_debug"
@@ -587,6 +635,10 @@
         '  "target_cpu": "arm64"'
         '}'
       service_account: "openscreen-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
     }
     builders {
       name: "mac_debug"
@@ -620,6 +672,10 @@
         path: "osx_sdk"
       }
       service_account: "openscreen-try-builder@chops-service-accounts.iam.gserviceaccount.com"
+      experiments {
+        key: "luci.recipes.use_python3"
+        value: 100
+      }
     }
     builders {
       name: "openscreen_presubmit"
diff --git a/infra/config/global/main.star b/infra/config/global/main.star
index c165359..934438e 100755
--- a/infra/config/global/main.star
+++ b/infra/config/global/main.star
@@ -176,14 +176,12 @@
         cpu: the target central processing unit.
     """
     recipe_id = "openscreen"
-    use_python3 = False
+    use_python3 = True
     if properties:
         if "builder_group" in properties:
             recipe_id = "chromium"
-            use_python3 = True
         elif "runhooks" in properties:
             recipe_id = "run_presubmit"
-            use_python3 = True
 
     caches = []
     if os == MAC_VERSION: