Use the default HMACSHA1 constructor for an explicit false selector

Replace attributed new HMACSHA1(key, false) with new HMACSHA1(key): the Framework one-argument constructor delegates to the two-argument constructor with false. Preserve key evaluation and object initialization. A named useManagedSha1: false selector is also supported. True/computed selectors, named keys, unresolved calls, comments on the removed argument, and conditional snapshots remain unchanged. Does not change the hash algorithm. Lambda/query contexts remain unchanged.