gooftool: remove created temporary report archive

The CreateReportArchiveBlob function won't remove created archive file
by itself.  Therefore, a lot of temporary files will keep under /tmp/
directory.  Delete the report archive after read out the content.

BUG=None
TEST=manual

Change-Id: I5e40ca9b22c775ec6e93bdbc090d98dd82a63b29
Reviewed-on: https://chromium-review.googlesource.com/385396
Commit-Ready: Wei-Han Chen <stimim@chromium.org>
Tested-by: Wei-Han Chen <stimim@chromium.org>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
diff --git a/py/gooftool/commands.py b/py/gooftool/commands.py
index bd304b1..0ecf77b 100755
--- a/py/gooftool/commands.py
+++ b/py/gooftool/commands.py
@@ -561,8 +561,12 @@
   Returns:
     An xmlrpclib.Binary object containing a .tar.xz file.
   """
-  with open(CreateReportArchive(*args, **kwargs)) as f:
-    return xmlrpclib.Binary(f.read())
+  report_archive = CreateReportArchive(*args, **kwargs)
+  try:
+    with open(report_archive) as f:
+      return xmlrpclib.Binary(f.read())
+  finally:
+    os.unlink(report_archive)
 
 
 def CreateReportArchive(device_sn=None, add_file=None):