Remove 32 bit arm CPU support for agentk

Prior discussion in gitlab-org&10045 (comment 1820193361).

Some time ago we added arm 32 bit support and arm64 support for agentk images.

At the moment CNG doesn't support arm64 yet, but this is being worked on. Once it does, we would still not be able to move agentk builds there because of our 32 bits support.

Do we want to drop arm 32 bit support or do we want to keep it? To be extra clear - we don't need to and don't want to drop arm64 support.

"Keep" benefits:

• There are (probably) users that use 32 bit agentk.
  • How many?

"Drop" benefits:

• kas and agentk build can be unified in CNG and Omnibus. We currently build kas in CNG/Omnibus and agentk in the canonical repo.
• Release process can be streamlined. We can fully rely on release-tools.
• Security release process can be streamlined. We don't have a proper security release process for agentk (we do for kas since recently).