Add enum value for error update download canceled per policy

This CL adds error code for update download canceled due to
DeviceAutoUpdateTimeRestrictions policy to the
enum so that it can be reflected in the histogram. This error code is
already added in update engine code in the following CL -
https://chromium-review.googlesource.com/c/aosp/platform/system/update_engine/+/2567121

Bug: chromium:1117450
Change-Id: I2c67b1799d9f121fbda8e84491723d41116d5fe3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2593383Reviewed-by: Maksim Ivanov <emaxx@chromium.org>
Commit-Queue: Saurabh Nijhara <snijhara@google.com>
Cr-Commit-Position: refs/heads/master@{#838016}

tools/metrics/histograms/enums.xml

@@ -74707,6 +74707,7 @@ Full version information for the fingerprint enum values:
   <int value="60" label="kErrorCodeNotEnoughSpace"/>
   <int value="61" label="kErrorCodeDeviceCorrupted"/>
   <int value="62" label="kErrorCodePackageExcludedFromUpdate"/>
+  <int value="63" label="kErrorCodeDownloadCancelledPerPolicy"/>
 </enum>
 
 <enum name="UpdateEngineInstallDateProvisioningSource">