When a scope with `activates: :all` fired during file change detection
(e.g. root_config), it activated ALL groups passed to
`activate_from_scopes` — including groups with `ignore_global_scope:
true`. This meant groups that explicitly opted out of global activation
were still pulled in whenever a broadly-scoped trigger (like
`.buildkite/**`) fired on main.

The fix filters groups in the `activates: :all` path: groups with
`ignore_global_scope` are only included if their own scope also fired.