Lawrence Tynes kicked the Giants into two Super Bowls, and those highlights will forever be a part of franchise lore. But nothing lasts forever and, after six seasons, he is moving on because the Giants already have replaced him. Tynes is an unrestricted free agent and the Giants Wednesday landed his likely successor, signing Josh Brown, a 10-year veteran, to a one-year, salary cap-friendly deal. “Josh is an experienced, proven kicker in this league,” general manager Jerry Reese said. “Just like we try to do at every position, we expect great competition for the placekicking job, and that will only make us better.” Figure the competition will be won by Brown. Already this offseason, the Giants signed David Buehler, who is known as a kickoff specialist from his time with the Cowboys (2009-11). Buehler, 26, did not kick in the NFL last season and Brown — who turns 34 next month — is the heavy favorite to emerge from the kicking derby. Tynes turns 35 in May and wanted to return to the Giants, but is looking for a multi-year deal. The Giants wouldn’t make that commitment. “It’s a great opportunity for me, an opportunity to be a part of a very storied franchise,’’ Brown said. “I’m excited.’’