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 steep professional decline and evicted from her suite in a Los Angeles hotel, Garland is forced to leave …