At the end of the rainbow there is a dark and stormy night.“Judy,” starring Renee Zellweger as the big-voiced, doe-eyed, tissue-frail Judy Garland, portrays the last year of Garland’s life, bridging the summer of 1968 until her death from a barbiturate overdose at age 47 in 1969. The screenplay is based on the British playwright Peter Quilter’s 2005 stage play, “End of the Rainbow.”In …