FR-5713 - Clean image build leftovers

[upils]

No description provided.

[codecov]

Codecov Report

Merging #155 (84a2e75) into main (aeff22c) will decrease coverage by 0.28%.
Report is 1 commits behind head on main.
The diff coverage is 70.58%.

@@            Coverage Diff             @@
##             main     #155      +/-   ##
==========================================
- Coverage   90.53%   90.25%   -0.28%     
==========================================
  Files          11       11              
  Lines        2471     2505      +34     
==========================================
+ Hits         2237     2261      +24     
- Misses        208      213       +5     
- Partials       26       31       +5     

Files	Coverage Δ
internal/statemachine/state_machine.go	98.03% <ø> (ø)
internal/statemachine/classic_states.go	96.20% <70.58%> (-1.08%)	⬇️

[waveform80]

This looks sane to me, and many thanks for picking up on the debconf/dpkg clean-up. Checked the Pi images again, and those *-old files are indeed present so this is certainly still needed too.

[sil2100]

I like the idea of having a separate state for this, very clean. LGTM.