test: enable geth tests again

[mattsse]

🤖 Generated by Copilot at 931abfe

This pull request enhances the integration tests for the net crate by using a feature flag for Geth, reactivating some skipped tests, and simplifying the port setup in connect.rs.

[codecov]

Codecov Report

Merging #4544 (931abfe) into main (fc9f116) will increase coverage by 0.01%.
The diff coverage is n/a.

see 17 files with indirect coverage changes

Flag	Coverage Δ
integration-tests	16.74% <ø> (+0.05%)	⬆️
unit-tests	63.95% <ø> (-0.01%)	⬇️

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Components	Coverage Δ
reth binary	30.83% <ø> (ø)
blockchain tree	83.58% <ø> (ø)
pipeline	90.56% <ø> (ø)
storage (db)	75.32% <ø> (ø)
trie	94.88% <ø> (ø)
txpool	47.50% <ø> (ø)
networking	77.52% <ø> (+0.08%)	⬆️
rpc	57.35% <ø> (-0.01%)	⬇️
consensus	63.40% <ø> (ø)
revm	31.67% <ø> (ø)
payload builder	6.34% <ø> (ø)
primitives	86.50% <ø> (-0.01%)	⬇️