Force Mac build_tests to run on x64 bots (#120620)

Author: jmagman

.ci.yaml

@@ -2500,6 +2500,7 @@ targets:
     timeout: 60
     properties:
       add_recipes_cq: "true"
+      cpu: x86 # https://github.com/flutter/flutter/issues/120292
       dependencies: >-
         [
           {"dependency": "android_sdk", "version": "version:33v6"},
@@ -2519,6 +2520,7 @@ targets:
     timeout: 60
     properties:
       add_recipes_cq: "true"
+      cpu: x86 # https://github.com/flutter/flutter/issues/120292
       dependencies: >-
         [
           {"dependency": "android_sdk", "version": "version:33v6"},
@@ -2538,6 +2540,7 @@ targets:
     timeout: 60
     properties:
       add_recipes_cq: "true"
+      cpu: x86 # https://github.com/flutter/flutter/issues/120292
       dependencies: >-
         [
           {"dependency": "android_sdk", "version": "version:33v6"},
@@ -2557,6 +2560,7 @@ targets:
     timeout: 60
     properties:
       add_recipes_cq: "true"
+      cpu: x86 # https://github.com/flutter/flutter/issues/120292
       dependencies: >-
         [
           {"dependency": "android_sdk", "version": "version:33v6"},