cros: Update |kRlzEmbargoEndDateGarbageDateThresholdDays| value

Because the factory already adds 7 days to the actual date, the
threshold should only add 7 days to rlz_embargo_end_date.

Bug: 820783
Change-Id: I97a599b2f893493ac91910f449051ec5a0ea7807
Reviewed-on: https://chromium-review.googlesource.com/1007962Reviewed-by: Roger Tawa <rogerta@chromium.org>
Commit-Queue: Wenzhao (Colin) Zang <wzang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550016}

rlz/chromeos/lib/rlz_value_store_chromeos.cc

@@ -118,8 +118,7 @@ bool HasRlzEmbargoEndDatePassed() {
 
 }  // namespace
 
-const int RlzValueStoreChromeOS::kRlzEmbargoEndDateGarbageDateThresholdDays =
-    14;
+const int RlzValueStoreChromeOS::kRlzEmbargoEndDateGarbageDateThresholdDays = 7;
 
 const int RlzValueStoreChromeOS::kMaxRetryCount = 3;