bootstat: test: check ro.boot.bootreason in some tests

blind_reboot_test() did not report the ro.boot.bootreason value,
making it more difficult to diagnose failures.

Test: system/core/bootstat/boot_reason_test.sh cold warm hard
Bug: 63736262
Change-Id: I313cfef202b1e06c583b0b47cd5d0e0888a7dbe7
diff --git a/bootstat/boot_reason_test.sh b/bootstat/boot_reason_test.sh
index ffe3dc7..af65135 100755
--- a/bootstat/boot_reason_test.sh
+++ b/bootstat/boot_reason_test.sh
@@ -569,6 +569,8 @@
   esac
   adb reboot ${TEST}
   wait_for_screen
+  bootloader_reason=`validate_property ro.boot.bootreason`
+  EXPECT_PROPERTY ro.boot.bootreason ${bootloader_reason}
   EXPECT_PROPERTY sys.boot.reason ${reason}
   EXPECT_PROPERTY persist.sys.boot.reason ${reason}
   report_bootstat_logs ${reason}