Deprecate user building features

### Requirement

As we're providing feature parity between `IntegrationProfile` and the old `IntegrationPlatform` (#6705) we should remove the following features:

- builder trait: move builder properties to camel trait instead
- integration repositories: only inherit those available in the profile.

We must introduce a deprecation notice to enable future removal. We want to only enable certain build features via an administrative role (for example, via the creation of profiles).

Beside those we should enable the following policies in the profile (and default env var):

- enable Quarkus native: to make this option available via profile only
- quarkus images to use: use only the one provided in the profile (via allowlist)
- base images: use only the one provided in the profile (via allowlist)

Start by reading the IntegrationProfile and IntegrationPlatform implementations and the existing builder, camel trait, and integration repository handling. Trace how profile policies and environment defaults are applied. Done means the listed user-building features are deprecated, profile repositories are restricted, and native, Quarkus image, and base-image policies use profile allowlists.

Written by the indexing model from the issue text.