Holyoke will experience its first “midterm” election in 2019. It may be easy forget as he is running for something, but Alex Morse is not on the ballot this year. The four-term mayor is halfway through his first four-year mayoral term. But the City Council and much of the School Committee remain on a two-year election cycle. Voters rejected doubling councilors’ term in 2015 even as they lengthened the mayoral term to four years.