MANILA — President Trump vowed this week to reclaim the United States’ role as a Pacific power. But as he wrapped up a marathon tour of Asia on Tuesday, Trump’s mixed messages left allies unsure of the United States’ staying power and fed a growing sense that China, not the United States, drives the agenda in the region. Whether recruiting partners to confront North Korea even as he castigated them for trade abuses, or embracing China at the same time that he lined up a like-minded coalition to contain it, Trump was often a bewildering figure to countries that had already viewed the new president with anxiety.