gpl: revert PR #11553 for momentum reset

[gudeh]

The momentum reset is causing the step length on some private designs to be too small and instances are not moving at all after their 2nd TD iteration.

Revert the changes from #11553 while I search for a solution.

[gemini-code-assist]

Code Review

This pull request removes the reset_nesterov_momentum_ logic from the NesterovPlace class and deletes the associated simple01-td-restart test case, as this momentum restart mechanism is no longer required. The test output files have been updated to reflect these changes. I have no feedback to provide.

[gudeh]

I noticed that increasing the minimum step-length from 0.01 to 0.1 makes the issue go away. But I am working on a proper solution with a proper understanding of the whole issue.

OpenROAD/src/gpl/src/nesterovBase.cpp

Lines 4392 to 4395 in ff92ebf

	if (newStepLength < 0.01) {
	stepLength_ = 0.01;
	return false;
	}

[gudeh]

@jhkim-pii FYI

[jhkim-pii]

Oh there is a side effect. Thank you for sharing.