[node-split] Tune PoC startup script

[jellonek]

As in the title.

Extracted from #6506

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.2%. Comparing base (49bbb0b) to head (7e9ad71).
Report is 1 commits behind head on node-split-poc.

Additional details and impacted files

@@              Coverage Diff               @@
##           node-split-poc   #6520   +/-   ##
==============================================
  Coverage            77.2%   77.2%           
==============================================
  Files                 342     342           
  Lines               45839   45839           
==============================================
  Hits                35391   35391           
- Misses               8330    8338    +8     
+ Partials             2118    2110    -8     

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[ivan4th]

docker images docs do not seem to indicate guaranteed order of the items listed, so it's not very reliable to do this. You may want to use

docker images --format json | jq -rs 'sort_by(.CreatedAt)|last|.ID'

or follow this approach

[ivan4th]

This is probably not very important for a PoC, but given that this snippet may be copied later for some other use and then wrong image may be used, leading to unwanted surprises, we may want to be more careful ;)