SACRAMENTO, Calif. — Thousands of California migrant farmworkers must leave their affordable housing every year when the state closes the complexes seasonally — now a Central Valley lawmaker and a legislative leader want to change that. Assemblyman Joaquin Arambula, D-Fresno, on Thursday announced plans to introduce a bill that would instruct the California Department of Housing and Community Development to keep its 24 migrant farmworker housing complexes open year-round. Assembly Speaker Robert Rivas, D-Hollister, is a co-author of the measure. Arambula authored Assembly Bill 2240 after a Sac…