Remove .cipd-cache and third_party/depot_tools/.cipd_bin/.cipd

To make the build hermetic.
After this CL, on my workstation, regenerating the chrome soruce
tarball no longer results in rebuilding chromeos-chrome.

BUG=b:304441605
TEST=bazel build @portage//chromeos-base/chromeos-chrome

Change-Id: I4ac8b5dbf82460c91ed933055b8b37716dcf8b0b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/bazel/+/4951533
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Tested-by: Ryo Hashimoto <hashimoto@chromium.org>
Commit-Queue: Ryo Hashimoto <hashimoto@chromium.org>

portage/repo_defs/chrome/cros_chrome_repository.bzl

@@ -122,9 +122,8 @@ def _cros_chrome_repository_impl(ctx):
         "--transform=flags=rSh;s,^,/home/root/chrome_root/,",
     ]
 
-    # Remove .cipd-cache/instances/state.db as there is no guarantee about its
-    # contents. CIPD will regenerate it if needed.
-    ctx.delete(".cipd-cache/instances/state.db")
+    # Remove CIPD cache files to make this hermetic.
+    ctx.delete("src/third_party/depot_tools/.cipd_bin/.cipd")
 
     # We use zstd since it's way faster than gzip and should be installed by
     # default on most distributions. Hopefully the compression algorithm doesn't
@@ -143,12 +142,14 @@ def _cros_chrome_repository_impl(ctx):
             # Hashes of all the dependencies. Useful since we don't include the
             # .git directories.
             ".gclient_entries",
-            # cipd lookup cache
-            ".cipd-cache",
             # We don't include the .vpython-root since it contains absolute
             # symlinks which we can't use inside the chroot. Since we have the
             # cache and pkgs we can recreate it in the chroot without network
             # access.
+
+            # We don't include the .cipd-cache because it's not hermetic.
+            # TODO(b/304441605): Consider including it to avoid performing
+            # network IO when building chrome.
         ],
         ZSTD_NBTHREADS = "0",
         msg = "Tarring up Chromium src",