std::rt: Run local storage cleanup and the box annihilator inside the try/catch

And before collect_failure. These are both running user dtors and need to be handled
in the task try/catch block and before the final task cleanup code.
auto merge of #8269 : brson/rust/fix-task-cleanup, r=brson

...y/catch

And before collect_failure. These are both running user dtors and need to be handled
in the task try/catch block and before the final task cleanup code.