Disable autoupdate_Rollback.powerwash_before_rollback.

Due to various cherry picks to M86 this test will try to cleanup by
restoring stateful but the code wasn't ready in M86. This is causing all
boards to have red builds on the LTS branch. So disable them.

BUG=b:192561770
TEST=None

Change-Id: If2cad56f9dd9ab26da979b0c81c82c5ab531778e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/3018583
Tested-by: David Haddock <dhaddock@chromium.org>
Auto-Submit: David Haddock <dhaddock@chromium.org>
Reviewed-by: Derek Beckett <dbeckett@chromium.org>
Commit-Queue: Derek Beckett <dbeckett@chromium.org>
diff --git a/server/site_tests/autoupdate_Rollback/control.powerwash_before_rollback b/server/site_tests/autoupdate_Rollback/control.powerwash_before_rollback
index be073e4..e4a7d35 100644
--- a/server/site_tests/autoupdate_Rollback/control.powerwash_before_rollback
+++ b/server/site_tests/autoupdate_Rollback/control.powerwash_before_rollback
@@ -10,7 +10,6 @@
 TEST_CATEGORY = "Functional"
 TEST_CLASS = "platform"
 TEST_TYPE = "server"
-ATTRIBUTES = "suite:bvt-installer"
 
 DOC = """
 This is a rollback test for Chrome OS releases. It first updates a machine and