Rejecting critics and community concern, voting members of Seattle’s Group Health Cooperative have overwhelmingly agreed to join with the California health-care giant Kaiser Permanente. Voting 8,824 to 1,586 in mailed-in ballots, the members approved the move that essentially dissolves the iconic, home-grown cooperative, founded nearly 70 years ago with the mission of providing integrated health care and health coverage to Northwest residents. The results of the vote were announced Saturday at a meeting at Seattle’s Smith Cove Cruise Terminal that was attended by about 300 co-op members out of an expected 1,000.