Fix ota test case

It was failing with:
build/make/core/main.mk:2: Calling make directly is no longer supported.
build/make/core/main.mk:3: Either use 'envsetup.sh; m' or 'build/soong/soong_ui.bash --make-mode'
build/make/core/main.mk:4: *** done.  Stop.

Test: system/core/bootstat/boot_reason_test.sh ota
Change-Id: I4fea25f1c09e6ec2f346b6de3749699e254ffd26