Revert accepting pending Os to accept traffic

[leszko]

What does this pull request do? Explain your changes. (required)

After the Arbitrum migration, we should move to the logic as before, meaning that only active Os can accept transcoding.

Related Discord discussion: https://discord.com/channels/423160867534929930/750796877762527262/1074970658544558092

This PR is an exact revert of these PRs: #2188 and #2146

Specific updates (required)

How did you test each of these updates (required)

Tested locally with local dev geth

Does this pull request close any open issues?

Checklist:

• Read the contribution guide
• make runs successfully
• All tests in ./test.sh pass
• README and other documentation updated
• Pending changelog updated

[codecov]

Codecov Report

Merging #2758 (d6c76a3) into master (a8f3f4e) will decrease coverage by 0.03161%.
The diff coverage is 100.00000%.

@@                 Coverage Diff                 @@
##              master       #2758         +/-   ##
===================================================
- Coverage   56.30182%   56.27021%   -0.03161%     
===================================================
  Files             88          88                 
  Lines          19177       19170          -7     
===================================================
- Hits           10797       10787         -10     
- Misses          7788        7791          +3     
  Partials         592         592                 

Impacted Files	Coverage Δ
core/orchestrator.go	77.87115% <100.00000%> (-0.06181%)	⬇️
discovery/db_discovery.go	69.11765% <100.00000%> (-1.64047%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 2f467db...d6c76a3. Read the comment docs.

Impacted Files	Coverage Δ
core/orchestrator.go	77.87115% <100.00000%> (-0.06181%)	⬇️
discovery/db_discovery.go	69.11765% <100.00000%> (-1.64047%)	⬇️