(jenkins-jobs) Allow disabling /customizing build strategies without changing the branch discoveries

[dduportal]

What feature do you want to see added?

• By default, the build build strategies should be bound to the associated discovery (ref. (jenkins-jobs) Allow customization of the "Branch Discovery" trait #1210, (jenkins-jobs) Allow customization of the "Discover origin pull requests" trait #1211 and (jenkins-jobs) Allow customization of the "Discover fork pull requests" trait #1212 for instance).
• BUT we want to be able to disable / customize the branch build strategies without changing the discovery

For instance:

• Discover tags but NEVER build them (unless a human trigger a build)
• Discover fork PRs (external contributors) but do NOT build them (unless a human trigger a build)

Upstream changes

No response