internal/godebugs: fix old value for httpservecontentkeepheaders

The pre-Go 1.23 behavior is httpservecontentkeepheaders=1.

For #66343

Change-Id: If6f92853b38522f19a8908ff11ac49b12f3dc3e0
Reviewed-on: https://go-review.googlesource.com/c/go/+/593775
Reviewed-by: David Chase <[email protected]>
Auto-Submit: Damien Neil <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: neild

src/internal/godebugs/table.go

@@ -36,7 +36,7 @@ var All = []Info{
 	{Name: "http2server", Package: "net/http"},
 	{Name: "httplaxcontentlength", Package: "net/http", Changed: 22, Old: "1"},
 	{Name: "httpmuxgo121", Package: "net/http", Changed: 22, Old: "1"},
-	{Name: "httpservecontentkeepheaders", Package: "net/http", Changed: 23, Old: "0"},
+	{Name: "httpservecontentkeepheaders", Package: "net/http", Changed: 23, Old: "1"},
 	{Name: "installgoroot", Package: "go/build"},
 	{Name: "jstmpllitinterp", Package: "html/template", Opaque: true}, // bug #66217: remove Opaque
 	//{Name: "multipartfiles", Package: "mime/multipart"},