Include whether `postUpgradeTasks` runs on a branch with determining a branch fingerprint

When https://github.com/rootlyhq/rootly-go/pull/176 was created (2026-09-13T18:11:23Z), it did not have a go generate command wired in.

This wasn't correctly added https://github.com/rootlyhq/rootly-go/pull/177 (2026-09-13T19:52:02Z), as it wasn't noticed that https://github.com/rootlyhq/rootly-go/pull/175 (2026-09-13T17:36:32Z) incorrectly matched

However, when correcting the config, we now don't get a rebase request created because:

2026-09-13T20:01:59.944Z  Converting rebaseWhen=auto to rebaseWhen=conflicted because no rule for behind-base-branch applies
2026-09-13T20:01:59.944Z  Branch already exists
2026-09-13T20:01:59.944Z  Skipping behind base branch check due to rebaseWhen=conflicted
2026-09-13T20:01:59.945Z  isBranchConflicted(master, renovate/go-toolchain)
2026-09-13T20:01:59.946Z  branch.isConflicted(): using cached result "false"
2026-09-13T20:01:59.946Z  Branch does not need rebasing
2026-09-13T20:01:59.946Z  Using reuseExistingBranch: true
2026-09-13T20:02:00.130Z  Status check renovate/stability-days is already up-to-date
2026-09-13T20:02:00.137Z  Checking if we can automerge branch
2026-09-13T20:02:00.137Z  mergeStatus=no automerge
2026-09-13T20:02:00.138Z  Ensuring PR
2026-09-13T20:02:00.138Z  There are 0 errors and 0 warnings

We should make sure that the postUpgradeTasks' config is included, so we don't treat a base branch that isn't modified as up-to-date if there are potential changes that could come from postUpgradeTasks.

As part of this, this should only include whether there are changes to the command, or affected file(s), as part of this.

Moved from #46113