Fix waitForProposerWindow

[StephenButtolph]

Why this should be merged

This fixes a testing helper used in the proposervm.

How this works

MinDelayForProposer returns the delay on top of the parent timestamp. Because of this, the returned delay is guaranteed to increase between loop iterations. This means that if the loop ever loops, it will keep looping. ➿

How this was tested

n/a

Need to be documented in RELEASES.md?

[Copilot]

Pull Request Overview

This PR fixes a bug in the waitForProposerWindow testing helper function in the proposervm that was causing an infinite loop. The fix addresses the incorrect loop termination condition and improves the clock advancement logic.

• Corrected the loop termination condition from checking delay against MaxLookAheadWindow to checking if current time has passed the required delay time
• Fixed clock advancement to occur after the termination check instead of before
• Added intermediate variable delayUntil for clearer time calculations

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