[onert] Refactor on-device compiler build verification process

[hseok-oh]

What

#16051 is temporary policy.
Let's refactor on-device compiler build verification process after sync up gbs build.

Why

1. Building on-device compiler takes long for PR check
2. Sync-up external source dependency on GBS build is not easy

So let's change verification policy

• Revive on-device compiler default build option in nnfw.spec file
• Disable on PR check by gbs build option

Then PR check will skip on-device compiler build, but that will be verified by internal system.