cbuildbot_launch: Remove legacy cleanup from cache

With the move to an overlayfs approach, and no named cache, we can
remove the cleanup that is a bit too aggressive and results in emptying
the directory completely, which in turn requires a full sync on every
bot.

BUG=b:186752777
TEST=`run_tests`

Cq-Depend: chromium:2911033
Change-Id: Iede42c22f681fbc2205893f86a942496ac08ea1a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2911118
Reviewed-by: LaMont Jones <lamontjones@chromium.org>
Tested-by: Mike Nichols <mikenichols@chromium.org>
Commit-Queue: Mike Nichols <mikenichols@chromium.org>
diff --git a/scripts/upload_prebuilts_unittest.py b/scripts/upload_prebuilts_unittest.py
index 256534f..ff0912b 100644
--- a/scripts/upload_prebuilts_unittest.py
+++ b/scripts/upload_prebuilts_unittest.py
@@ -119,7 +119,7 @@
   """Tests for Prebuilt logic."""
 
   def setUp(self):
-    self._base_local_path = '/b/cbuild/build/chroot/build/x86-dogfood/'
+    self._base_local_path = '/b/chromiumos/build/chroot/build/x86-dogfood/'
     self._gs_bucket_path = 'gs://chromeos-prebuilt/host/version'
     self._local_path = os.path.join(self._base_local_path, 'public1.tbz2')