cmd/go: temporarily skip TestScript/test_fuzz_minimize

This test is failing on the longtest builders.
Adding a skip temporarily until it can be diagnosed and fixed.

For #49685

Change-Id: I0ceaf009f5029d1ad6f667f7cfee1f1605737bf3
Reviewed-on: https://go-review.googlesource.com/c/go/+/365315


Trust: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>