Re-generate 4K boot OTAs using signed boot.img during signing process

Currently, dev option OTAs are generated using dev-key signed boot.img
On release-key devices, OTA will install successfully, but user would be
using dev-key signed boot image after reverting to 4K mode, and
subsequent OTAs would fail. This CL re-generates 4K boot OTA using
release-key signed boot.img , which allows normal OTAs after toggling
dev options.

Test: th
Bug: 354019928
Change-Id: I40811d6ed7a37f50edea77d245bf559b66da5a71