Stop building boot-(debug|with-debug-ramdisk)-*.img for GSI/GKI

We don't need these anymore as we now export userdebug_plat_sepolicy.cil
to artifacts dist dir directly, so repack_bootimg don't need to use
boot-(debug|with-debug-ramdisk)-*.img as repack source anymore.

Bug: 202129499
Test: Check presubmit artifacts don't have boot-*debug*.img
Change-Id: I3161e42b00a93177a1a4cb3b22da2218d294b7a7