layout: skip creation of pack subdirectories in integration tests

Each time a local backend is created, the local backend also creates all
shard subdirectories. For the integration tests this has the downside
that this results in ~120 (number of test) * 256 (number of directories)
= 30k directories that are created unnecessarily. This significantly
slows down test execution and cleanup.

cmd/restic/cmd_init_integration_test.go

@@ -25,6 +25,7 @@ func testRunInit(t testing.TB, gopts global.Options) {
 
 	// create temporary junk files to verify that restic does not trip over them
 	for _, path := range []string{"index", "snapshots", "keys", "locks", filepath.Join("data", "00")} {
+		rtest.OK(t, os.MkdirAll(filepath.Join(gopts.Repo, path), 0700))
 		rtest.OK(t, os.WriteFile(filepath.Join(gopts.Repo, path, "tmp12345"), []byte("junk file"), 0o600))
 	}
 }

cmd/restic/integration_helpers_test.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/restic/restic/internal/backend"
 	"github.com/restic/restic/internal/backend/all"
+	"github.com/restic/restic/internal/backend/layout"
 	"github.com/restic/restic/internal/backend/retry"
 	"github.com/restic/restic/internal/data"
 	"github.com/restic/restic/internal/errors"
@@ -192,6 +193,7 @@ func withTestEnvironment(t testing.TB) (env *testEnvironment, cleanup func()) {
 	repository.TestUseLowSecurityKDFParameters(t)
 	restic.TestDisableCheckPolynomial(t)
 	retry.TestFastRetries(t)
+	layout.TestDisablePackSubdirs(t)
 
 	tempdir, err := os.MkdirTemp(rtest.TestTempDir, "restic-test-")
 	rtest.OK(t, err)