Cleanup skale-manager image after deployment. Fix tests

[badrogger]

Remove skale-manager docker image to reduce occupied disk space.
No source code touched, no performance changes made.

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (456bc4d) 80.45% compared to head (b6b09a3) 80.40%.
Report is 4 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #996      +/-   ##
===========================================
- Coverage    80.45%   80.40%   -0.05%     
===========================================
  Files          100      100              
  Lines         5501     5523      +22     
===========================================
+ Hits          4426     4441      +15     
- Misses        1075     1082       +7     

Files	Coverage Δ
core/schains/monitor/action.py	90.32% <100.00%> (-1.32%)	⬇️
core/schains/monitor/containers.py	78.46% <100.00%> (ø)
core/schains/monitor/skaled_monitor.py	92.50% <100.00%> (-0.10%)	⬇️
tools/docker_utils.py	96.20% <81.81%> (-0.75%)	⬇️

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