op-node: Refactor step scheduling events

[mslipper]

Refactors the following events by converting them into synchronous method calls:

• StepReqEvent
• ResetStepBackoffEvent
• StepDelayedReqEvent

I tried to refactor StepEvent as well, but ran into some issues with asynchrony in the action tests. I'll try that one again later.

[teddyknox]

LGTM, if it passes tests.

[codecov]

Codecov Report

❌ Patch coverage is 47.50000% with 21 lines in your changes missing coverage. Please review.
✅ Project coverage is 44.58%. Comparing base (b200250) to head (f52f54b).
⚠️ Report is 7 commits behind head on develop.

Files with missing lines	Patch %	Lines
op-node/rollup/driver/state.go	0.00%	12 Missing ⚠️
op-node/rollup/driver/steps.go	79.16%	4 Missing and 1 partial ⚠️
op-node/rollup/driver/driver.go	0.00%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #17093      +/-   ##
===========================================
- Coverage    45.81%   44.58%   -1.23%     
===========================================
  Files         1468     1413      -55     
  Lines       119406   114732    -4674     
===========================================
- Hits         54707    51157    -3550     
+ Misses       60862    59903     -959     
+ Partials      3837     3672     -165     

Flag	Coverage Δ
cannon-go-tests-64	?
contracts-bedrock-tests	96.29% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
op-node/rollup/driver/driver.go	0.00% <0.00%> (ø)
op-node/rollup/driver/steps.go	85.71% <79.16%> (+15.40%)	⬆️
op-node/rollup/driver/state.go	0.00% <0.00%> (ø)

... and 68 files with indirect coverage changes

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