zip: expand logging and use t.TempDir and t.Cleanup in test helpers

Fixes golang/go#55250 (for now).

Change-Id: I7286c459937e666d3e88fe56a9af1a2ff22f0186
Reviewed-on: https://go-review.googlesource.com/c/mod/+/432475
Auto-Submit: Bryan Mills <[email protected]>
Run-TryBot: Bryan Mills <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Michael Matloob <[email protected]>

Author: Bryan C. Mills