all: remove unnecessary loop variable copies in tests

all: remove unnecessary loop variable copies in tests

Copying the loop variable is no longer necessary since Go 1.22.

Change-Id: Iebb21dac44a20ec200567f1d786f105a4ee4999d
Reviewed-on: https://go-review.googlesource.com/c/go/+/711640
Reviewed-by: Florian Lehner <lehner.florian86@gmail.com>
Auto-Submit: Damien Neil <dneil@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>