Last week's program at the San Francisco Symphony carried a sense of celebration with it. John Adams was in attendance, giving luster to the orchestra's new performance and recording of his "Harmonielehre" under the direction of Michael Tilson Thomas. (Edo De Waart taped the piece in his final year as Music Director, when Adams was composer-in-residence.) There has always been a tendency to rally around the orchestra in San Francisco — cultural boosterism being one of the old-fashioned charms of this now rather important city, which sometimes still thinks of itself as a town and behaves like one in its enthusiasms — and John Adams is a local hero in the orchestra's history. But the spontaneous applause I heard on Saturday seemed to go beyond these boundaries. It is a though, from the standpoint of an audience, Adams were being hailed for having rescued contemporary music — and indeed, he just may have.