[spec] Omit "in:" spec problem info when reporting if all indexes

When reporting spec problems, function arg problems are almost always positional in nature (syntax), as defined in a regex spec. In those cases, reporting the "in:" data paths are often more confusing than useful.

For example:

Here, "In: [0 0]" is not helping me as a user understand the issue (although the data is helpful to error printers like expound). However, if these are nested s/keys specs, the in: data are keywords which provide a lot of information.

Proposed: When printing in the repl, if the explain printer is the default explain printer, remove all of the :in data from the explain-data problems before printing. (But don't do this if a custom printer is being used, like expound.)

Patch: clj-2396-3.patch