Installed updates leave obsolete control wrapper after a rename

[omry]

Summary

Updating an installed deployment after its generated control-script name changes
creates the new wrapper but leaves the previous Reploy-generated wrapper behind.

This was observed while adopting the new appctl default from #68 / PR #74.

Reproduction

1. Install a state-v1 system deployment whose blueprint explicitly sets:

   environment:
     id: arbiter
     control_script: arbiter
   

2. Update the blueprint to omit control_script, so current Reploy resolves the
   default appctl name.

3. Refresh the existing staging deployment. Staging correctly removes arbiter
   and creates appctl.

4. Rebuild and update the existing system installation:

   sudo reploy install \
     --dir reploy-staging \
     --scope system \
     --to /opt/arbiter \
     --service arbiter
   

5. Inspect the installation root.

Observed

Both wrappers remain:

/opt/arbiter/appctl
/opt/arbiter/arbiter

The old file is the previous generated wrapper and still embeds:

control_script='arbiter'

The new file embeds:

control_script='appctl'

Staging update behavior is correct: only reploy-staging/appctl remains.

Expected

When an installed deployment changes control-script names, Reploy should remove
the previous Reploy-managed wrapper after successfully installing the new one.
It must not remove an unrelated operator-owned file merely because it occupies
the previous path.

Add installed-update regression coverage matching the existing staged refresh
coverage for renamed wrappers.

Environment

• Reploy: 0.7.0.dev1 at 08d1ee835c
• System install target: /opt/arbiter
• Previous control script: arbiter
• Current control script: appctl