Recipes: make cwd default to slave_build

scripts/slave/recipes/infra/infra_continuous.expected/infra.json

Index: scripts/slave/recipes/infra/infra_continuous.expected/infra.json
diff --git a/scripts/slave/recipes/infra/infra_continuous.expected/infra.json b/scripts/slave/recipes/infra/infra_continuous.expected/infra.json
index 85558b95d038ef544abffa284f304b3a508396a0..fb6b0c801fa786b6986a11dd8453050ba7c804c7 100644
--- a/scripts/slave/recipes/infra/infra_continuous.expected/infra.json
+++ b/scripts/slave/recipes/infra/infra_continuous.expected/infra.json
@@ -28,6 +28,7 @@
       "infra@HEAD",
       "--force"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "bot_update",
     "~followup_annotations": [
       "@@@STEP_TEXT@Some step text@@@",
@@ -54,6 +55,7 @@
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "gclient runhooks"
   },
   {
@@ -74,6 +76,7 @@
       "python",
       "[SLAVE_BUILD]/infra/go/test.py"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "infra go tests"
   },
   {
@@ -85,6 +88,7 @@
       "--service-account-json",
       "/creds/service_accounts/service-account-cipd-builder.json"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "build cipd packages"
   }
 ]