add arm host builder (#23440)

ci/dev/prod_builders.json

@@ -12,6 +12,10 @@
          "name":"Linux Host Engine",
          "repo":"engine"
       },
+      {
+         "name":"Linux Arm Host Engine",
+         "repo":"engine"
+      },
       {
          "name":"Linux Fuchsia",
          "repo":"engine"

ci/dev/try_builders.json

@@ -25,6 +25,11 @@
          "repo":"engine",
          "enabled": true
       },
+      {
+         "name":"Linux Arm Host Engine",
+         "repo":"engine",
+         "enabled": true
+      },
       {
          "name":"Linux Web Engine",
          "repo":"engine",