testutil/promrated: add workflow and docker image for promrated

[LukeHackett12]

Adding build and deployment for promrated. Depends on https://github.com/ObolNetwork/obol-infrastructure/pull/329

category: misc
ticket: #1540

[codecov]

Codecov Report

Base: 54.16% // Head: 54.10% // Decreases project coverage by -0.06% ⚠️

Coverage data is based on head (ffc4ea1) compared to base (4a524f4).
Patch has no changes to coverable lines.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1574      +/-   ##
==========================================
- Coverage   54.16%   54.10%   -0.07%     
==========================================
  Files         157      157              
  Lines       19717    19711       -6     
==========================================
- Hits        10680    10664      -16     
- Misses       7589     7597       +8     
- Partials     1448     1450       +2     

Impacted Files	Coverage Δ
app/monitoringapi.go	80.00% <0.00%> (-1.46%)	⬇️
core/priority/prioritiser.go	60.48% <0.00%> (-1.21%)	⬇️
app/vmock.go	73.05% <0.00%> (-1.04%)	⬇️
app/app.go	63.63% <0.00%> (-0.69%)	⬇️
core/qbft/qbft.go	82.77% <0.00%> (-0.64%)	⬇️
app/metrics.go	100.00% <0.00%> (ø)
core/dutydb/memory.go	69.28% <0.00%> (+0.69%)	⬆️

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