Reland "bot_update: remove cleanup_dir"

This reverts commit e59e28f1d7.

Reason for revert: Fix up the issue line

Original change's description:
> Revert "bot_update: remove cleanup_dir"
>
> This reverts commit 4cebc13a4e.
>
> Reason for revert: this breaks Dart's builds
> https://ci.chromium.org/ui/p/dart/builders/ci.sandbox/dart2js-unit-linux-x64-release/27481/infra
>
> Original change's description:
> > bot_update: remove cleanup_dir
> >
> > when git cache is removed, gclient sync fails
> > and old checkout is moved into cleanup_dir.
> >
> > It will cause out of disk error during build
> > because cleanup_dir keeps full old checkout and build artifacts,
> > which is no longer needed when bot_update
> > succeeded to checkout.
> >
> > Remove cleanup_dir after checkout.
> >
> > Bug: 388307198
> > Change-Id: I3858e718622a1ef2012fe5b80a5d9b128d96d1d4
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6155955
> > Commit-Queue: Jie Sheng <jiesheng@google.com>
> > Reviewed-by: Yiwei Zhang <yiwzhang@google.com>
> > Auto-Submit: Fumitoshi Ukai <ukai@google.com>
> > Owners-Override: Jie Sheng <jiesheng@google.com>
> > Reviewed-by: Junji Watanabe <jwata@google.com>
> > Reviewed-by: Jie Sheng <jiesheng@google.com>
>
> Bug: 388307198
> Change-Id: Ifb68c1aaf28e2203ba2c3b5804c2fd4939bbd921
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6159604
> Auto-Submit: Alexander Thomas <athom@google.com>
> Reviewed-by: Jie Sheng <jiesheng@google.com>
> Commit-Queue: Yiwei Zhang <yiwzhang@google.com>
> Reviewed-by: Yiwei Zhang <yiwzhang@google.com>

Bug: 388307198
Change-Id: I1c6d922c357943882110233f84111a4cbfb9e7d4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6158861
Commit-Queue: Yiwei Zhang <yiwzhang@google.com>
Auto-Submit: Jie Sheng <jiesheng@google.com>
Reviewed-by: Yiwei Zhang <yiwzhang@google.com>

recipes/recipe_modules/bot_update/resources/bot_update.py

@@ -16,6 +16,7 @@ import optparse
 import os
 import pprint
 import re
+import shutil
 import subprocess
 import sys
 import tempfile
@@ -1142,7 +1143,16 @@ def checkout(options, git_slns, specs, revisions, step_text):
   properties['git_cache_epoch'] = cache_epoch
 
   usage = disk_usage()
-  # TODO(ukai): remove cleanup_dir if available disk space is small?
+  # successfully checked out. remove cleanup_dir to get free disk space.
+  if os.path.exists(options.cleanup_dir):
+    prev_usage = usage
+    print('Removing cleanup_dir %s' % options.cleanup_dir)
+    shutil.rmtree(options.cleanup_dir, ignore_errors=True)
+    usage = disk_usage()
+    print('Release %dGB (%d%%)' %
+          (prev_usage.used_disk_space_gb - usage.used_disk_space_gb,
+           prev_usage.percent_used - usage.percent_used))
+
   step_text = step_text + (' -> [%dGB/%dGB used (%d%%)]' % usage)
 
   # Tell recipes information such as root, got_revision, etc.