s3 cache misses print too much info to the log

[luser]

When we get a cache miss in S3 we hit this case:

sccache/src/cache/s3.rs

Line 82 in dda88a6

warn!("Got AWS error: {:?}", e);

Which winds up logging a whole unnecessary stacktrace (which can be especially useless on Windows):

WARN:sccache::cache::s3: Got AWS error: Error(BadHTTPStatus(Forbidden), State { next_error: None, backtrace: Some(stack backtrace:
   0:     0x7ff6cbaafac2 - <no info>
   1:     0x7ff6cbaaf5ae - <no info>
   2:     0x7ff6cbaaf62d - <no info>
   3:     0x7ff6cbaae93c - <no info>
   4:     0x7ff6cbaae9d3 - <no info>
   5:     0x7ff6cb9f3a5a - <no info>
   6:     0x7ff6cba0fb7c - <no info>
   7:     0x7ff6cb8d371d - <no info>
   8:     0x7ff6cb9feeb7 - <no info>
   9:     0x7ff6cb91d6dd - <no info>
  10:     0x7ff6cb84406a - <no info>
  11:     0x7ff6cba044dd - <no info>
  12:     0x7ff6cb9dab5d - <no info>
  13:     0x7ff6cb91db4d - <no info>
  14:     0x7ff6cb9ee930 - <no info>
  15:     0x7ff6cb91d92d - <no info>
  16:     0x7ff6cb9ca43c - <no info>
  17:     0x7ff6cba8dec0 - <no info>
  18:     0x7ff6cba8078f - <no info>
  19:     0x7ff6cb958b63 - <no info>
  20:     0x7ff6cb92c16a - <no info>
  21:     0x7ff6cb8b8655 - <no info>
  22:     0x7ff6cb824202 - <no info>
  23:     0x7ff6cb811006 - <no info>
  24:     0x7ff6cbb800f7 - <no info>
  25:     0x7ff6cbb9a442 - <no info>
  26:     0x7ff6cbb73a63 - <no info>
  27:     0x7ff6cb81105a - <no info>
  28:     0x7ff6cbbaff79 - <no info>
  29:     0x7ff88f7813d2 - BaseThreadInitThunk) })

We should probably match specifically for ErrorKind::BadHTTPStatus errors there and just log the status code for those. We could continue logging the entire error for other classes of errors.

[Xuanwo]

Fixed by #1404