infra_paths: remove deprecated slave_build

BUG=none

Change-Id: I8cf86841baf56288a3c5565dc7fae897e8789cd3
Reviewed-on: https://chromium-review.googlesource.com/446376
Reviewed-by: Sergiy Byelozyorov <sergiyb@chromium.org>
Commit-Queue: Paweł Hajdan Jr. <phajdan.jr@chromium.org>

recipe_modules/infra_paths/path_config.py

@@ -14,9 +14,6 @@ def infra_common(c):
 @CONFIG_CTX(includes=['infra_common'])
 def infra_buildbot(c):
   c.base_paths['root'] = c.START_DIR[:-4]
-  # slave_build is DEPRECATED in favor of start_dir
-  # TODO(nodir): remove it
-  c.base_paths['slave_build'] = c.START_DIR
   c.base_paths['cache'] = c.base_paths['root'] + (
       'build', 'slave', 'cache')
   c.base_paths['git_cache'] = c.base_paths['root'] + (
@@ -30,9 +27,6 @@ def infra_buildbot(c):
 @CONFIG_CTX(includes=['infra_common'])
 def infra_kitchen(c):
   c.base_paths['root'] = c.START_DIR
-  # slave_build is DEPRECATED in favor of start_dir
-  # TODO(nodir): remove it
-  c.base_paths['slave_build'] = c.START_DIR
   # TODO(phajdan.jr): have one cache dir, let clients append suffixes.
 
   b_dir = c.START_DIR