test: remove snapshot failure debugging code
test: remove snapshot failure debugging code

This code was added to aid in fixing issue #389,
which has since been fixed.

Change-Id: If60b6234f14495cdc3fd17e4a7c5150cdb6454e5
Reviewed-on: https://upspin-review.googlesource.com/10622
Reviewed-by: Rob Pike <4dc7c9ec434ed06502767136789763ec11d2c4b7@golang.org>

upspin/upspin,upspin/upspin