STT-1001 limit VLA scans per ScienceTarget
Fixed VLA scan list to have either one or three scans per ScienceTarget (ST), depending on the ST's total acquisition time(AT). AT now follows this flow: if total AT > 90, produce 3 scans each with AT = 1/3 * total AT if total AT < 1, produce one scan with AT = 1 second else, produce one scan with AT = total AT