SAN FRANCISCO — In a respect, it’s appropriate that a season featuring so many highs and so many lows ended with the Giants right in the middle. This is the space that the Giants have occupied since winning a franchise-record 107 games four years ago. And for the Giants, this season, one that ended with a 4-0 win over the Colorado Rockies, qualifies as the most frustrating of them all. The Giants, for their part, ended their season with positive vibrations. With Devers and Eldridge in the mix, Sunday afternoon likely marked Flores’ final game in a Giants uniform.