When the decider sees no point in another try, the park reason names the failing test and what each try changed #6576

"the decider saw no point in another try" leaves the planner to dig through closed pulls.

Done:

• [ ] The park reason the decider writes names the first failing test (or the deploy step) and, per try, the files the try changed, in at most three lines.
• [ ] Test: two red tries produce a reason naming the test and both tries' files.

Files: src/crew/decide.ts, src/crew/parks.ts, a test.