cmd/pkgserver: use IR cache for ident

This removes requirement to open full cache.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/pkgserver/main_test.go

@@ -10,17 +10,6 @@ import (
 	"testing"
 )
 
-// newIndex returns the address of a newly populated packageIndex.
-func newIndex(t *testing.T) *packageIndex {
-	t.Helper()
-
-	var index packageIndex
-	if err := index.populate(nil, nil); err != nil {
-		t.Fatalf("populate: error = %v", err)
-	}
-	return &index
-}
-
 // checkStatus checks response status code.
 func checkStatus(t *testing.T, resp *http.Response, want int) {
 	t.Helper()