Extend systest with option to add split node setup

[jellonek]

Motivation

Tune systests to run smeshers as pair of pods - node and activation.

Description

Note: split node setup will always deploy non smeshing node
to which there will be deployed connected n-1 activation nodes.
Because of that - node-split-size has to be set to 0 or >1.

Test Plan

Manual testing.

TODO

• Check if that's still working with OldSize != 0
• Validate with @kacpersaw if config/cmdline args for activation part is correct

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.3%. Comparing base (05ba7fb) to head (46b1975).
Report is 1 commits behind head on node-split-poc.

Additional details and impacted files

@@               Coverage Diff                @@
##           node-split-poc   #6506     +/-   ##
================================================
- Coverage            77.3%   77.3%   -0.1%     
================================================
  Files                 341     341             
  Lines               45737   45737             
================================================
- Hits                35378   35367     -11     
- Misses               8246    8254      +8     
- Partials             2113    2116      +3     

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[jellonek]

Closing in favor of #6520 #6521 and #6522 which contain the same changes splitted into 3 separate commits, which also are rebased on current top of the target branch.