Revert "all: add a handful of fuzz targets"

Revert "all: add a handful of fuzz targets"

This reverts CL 352109.

Reason for revert: causing OOM failures on several builders, and may cause OOMs for end users with small machines as well.

Change-Id: I58308d09919969d5a6512ee5cee6aa5c4af6769b
Reviewed-on: https://go-review.googlesource.com/c/go/+/377934
Trust: Bryan Mills <bcmills@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Katie Hockman <katie@golang.org>
Trust: Katie Hockman <katie@golang.org>