build: move e2e dependencies into e2e/go.mod

Several packages are only used while running the e2e suite. These
packages are less important to update, as the they can not influence the
final executable that is part of the Ceph-CSI container-image.

By moving these dependencies out of the main Ceph-CSI go.mod, it is
easier to identify if a reported CVE affects Ceph-CSI, or only the
testing (like most of the Kubernetes CVEs).

Signed-off-by: Niels de Vos <ndevos@ibm.com>

e2e/vendor/google.golang.org/protobuf/internal/flags/flags.go

@@ -0,0 +1,24 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package flags provides a set of flags controlled by build tags.
+package flags
+
+// ProtoLegacy specifies whether to enable support for legacy functionality
+// such as MessageSets, and various other obscure behavior
+// that is necessary to maintain backwards compatibility with proto1 or
+// the pre-release variants of proto2 and proto3.
+//
+// This is disabled by default unless built with the "protolegacy" tag.
+//
+// WARNING: The compatibility agreement covers nothing provided by this flag.
+// As such, functionality may suddenly be removed or changed at our discretion.
+const ProtoLegacy = protoLegacy
+
+// LazyUnmarshalExtensions specifies whether to lazily unmarshal extensions.
+//
+// Lazy extension unmarshaling validates the contents of message-valued
+// extension fields at unmarshal time, but defers creating the message
+// structure until the extension is first accessed.
+const LazyUnmarshalExtensions = ProtoLegacy

e2e/vendor/google.golang.org/protobuf/internal/flags/proto_legacy_disable.go

@@ -0,0 +1,10 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !protolegacy
+// +build !protolegacy
+
+package flags
+
+const protoLegacy = false

e2e/vendor/google.golang.org/protobuf/internal/flags/proto_legacy_enable.go

@@ -0,0 +1,10 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build protolegacy
+// +build protolegacy
+
+package flags
+
+const protoLegacy = true