cmd/go: update test_race_install expected output for CL 266368

test_race_install checks that 'go test -i -race …' does not rebuild
already installed packages, by also passing '-v' and verifying that no
package names are printed to stderr.

CL 266368 added a deprecation message for the '-i' flag that caused
the stderr output to be non-empty, although it still does not print
any package names.

Updates #41696

Change-Id: I13e10e49b7c33139be9b13f24cb393c9f58fd85d
Reviewed-on: https://go-review.googlesource.com/c/go/+/268581
Trust: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>

src/cmd/go/testdata/script/test_race_install.txt

@@ -6,12 +6,13 @@ go install -race -pkgdir=$WORKDIR/tmp/pkg std
 
 # Make sure go test -i -race doesn't rebuild cached packages
 go test -race -pkgdir=$WORKDIR/tmp/pkg -i -v empty/pkg
-! stderr .
+cmp stderr stderr.txt
 
 -- go.mod --
 module empty
 
 go 1.16
 -- pkg/pkg.go --
 package p
-
+-- stderr.txt --
+go test: -i flag is deprecated