Acu agent update line timestamp check

[mjrand]

Description

Added in a check for Point timestamps to add to update_lines in _run_track function in ACU agent.
This should added code should make sure that the update_lines list always contains at least ~3 * step_times worth of points.

Motivation and Context

We were seeing that the ACU agent _run_track function was running out of points during generate_scan calls when using non-standard (two_leg, standard_gen, three_leg) turnaround methods. This is because the turnaround_gen function generates PointTrack points at a step_time (currently 0.05s) that is much lower than the _run_track step_time (1.0s). The _run_track function tries to pull ~6 points per loop (which should be ~3 seconds worth of points). Because the turnaround_gen uses a much lower step_time, the _run_track function was struggling to keep up with the number of points needed per second. This change should make sure each loop of _run_track should always grab at least 3*step_time worth of points.

How Has This Been Tested?

Needs to be tested! We should test this on one of the platforms with the two_leg or standard_gen turnaround and watch the # free_position_points during turnarounds.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.