Revert "build: roll infra_paths changes"

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

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::bot_update]/resources/bot_update.py",
       "--master",
       "chromium.infra",
       "--builder",
       "luci-gae-linux64",
       "--slave",
       "TestSlavename",
       "--spec",
-      "cache_dir = '[ROOT]/b/build/slave/cache_dir'\nsolutions = [{'deps_file': '.DEPS.git', 'managed': True, 'name': 'infra', 'url': 'https://chromium.googlesource.com/infra/infra.git'}]",
+      "cache_dir = '[GIT_CACHE]'\nsolutions = [{'deps_file': '.DEPS.git', 'managed': True, 'name': 'infra', 'url': 'https://chromium.googlesource.com/infra/infra.git'}]",
       "--root",
       "infra/go/src/github.com/luci/gae",
       "--revision_mapping_file",
       "{\"infra/go/src/github.com/luci/gae\": \"got_revision\"}",
       "--git-cache-dir",
-      "[ROOT]/b/build/slave/cache_dir",
+      "[GIT_CACHE]",
       "--output_json",
       "/path/to/tmp/json",
       "--revision",
       "infra@origin/master",
       "--revision",
       "infra/go/src/github.com/luci/gae@c14d891d44f0afff64e56ed7c9702df1d807b1ee",
       "--revision",
       "infra/go/src/github.com/luci/luci-go@origin/master",
       "--force",
       "--output_manifest"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "bot_update",
     "~followup_annotations": [
       "@@@STEP_TEXT@Some step text@@@",
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"did_run\": true, @@@",
       "@@@STEP_LOG_LINE@json.output@  \"fixed_revisions\": {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"infra\": \"origin/master\", @@@",
@@ skipping 20 matching lines @@
       "@@@SET_BUILD_PROPERTY@got_revision_cp@\"refs/heads/master@{#34600}\"@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[depot_tools]/gclient.py",
       "runhooks"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "gclient runhooks"
   },
   {
     "cmd": [
       "python",
       "-u",
-      "[CWD]/infra/go/env.py",
+      "[SLAVE_BUILD]/infra/go/env.py",
       "go",
       "version"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "go third parties"
   },
   {
     "cmd": [
       "python",
       "-u",
-      "[CWD]/infra/go/env.py",
+      "[SLAVE_BUILD]/infra/go/env.py",
       "go",
       "build",
       "github.com/luci/gae/..."
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "go build"
   },
   {
     "cmd": [
       "python",
       "-u",
-      "[CWD]/infra/go/env.py",
+      "[SLAVE_BUILD]/infra/go/env.py",
       "go",
       "test",
       "github.com/luci/gae/..."
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "go test"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]