NETOBSERV-1792: Added update-build script to add downstream labels

[OlivierCazade]

Description

Added update-build script to add downstream labels

Dependencies

n/a

Checklist

If you are not familiar with our processes or don't know what to answer in the list below, let us know in a comment: the maintainers will take care of that.

• [X] Will this change affect NetObserv / Network Observability operator? If not, you can ignore the rest of this checklist.
• [ ] Is this PR backed with a JIRA ticket? If so, make sure it is written as a title prefix (in general, PRs affecting the NetObserv/Network Observability product should be backed with a JIRA ticket - especially if they bring user facing changes).
• [ ] Does this PR require product documentation?
  • [ ] If so, make sure the JIRA epic is labelled with "documentation" and provides a description relevant for doc writers, such as use cases or scenarios. Any required step to activate or configure the feature should be documented there, such as new CRD knobs.
• [ ] Does this PR require a product release notes entry?
  • [ ] If so, fill in "Release Note Text" in the JIRA.
• [ ] Is there anything else the QE team should know before testing? E.g: configuration changes, environment setup, etc.
  • [ ] If so, make sure it is described in the JIRA ticket.
• QE requirements (check 1 from the list):
  • [ ] Standard QE validation, with pre-merge tests unless stated otherwise.
  • [ ] Regression tests only (e.g. refactoring with no user-facing change).
  • [ ] No QE (e.g. trivial change with high reviewer's confidence, or per agreement with the QE team).