tests/integration: Moving integration tests to tests/integration directory

git mv integration ./tests

git mv client/integration/* ./tests/integration/client
git mv clientv3/integration/* ./tests/integration/clientv3
git mv client/example_keys_test.go client/main_test.go tests/integration/client/examples
git mv clientv3/concurrency/*_test.go tests/integration/clientv3/concurrency

git mv etcdserver/api/v2store/store_v2v3_test.go etcdserver/api/v2v3/*_test.go tests/integration/v2store
git mv tests/integration/v2store/store_v2v3_test.go tests/integration/v2store/store_v2v3.go
git mv tests/integration/v2store/store_test.go tests/integration/v2store/store_v2v3_test.go
git mv etcdserver/api/v2store/store_test.go tests/integration/v2store
git mv etcdserver/api/v2store/store_v2_test.go tests/integration/v2store

git mv proxy/grpcproxy/*_test.go tests/integration/proxy/grpcproxy

git mv ./clientv3/snapshot/testdata ./clientv3/snapshot/*_test.go ./tests/integration/snapshot

clientv3/concurrency/example_stm_test.go

@@ -1,97 +0,0 @@
-// Copyright 2017 The etcd Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package concurrency_test
-
-import (
-	"context"
-	"fmt"
-	"log"
-	"math/rand"
-	"sync"
-
-	"go.etcd.io/etcd/v3/clientv3"
-	"go.etcd.io/etcd/v3/clientv3/concurrency"
-)
-
-// ExampleSTM_apply shows how to use STM with a transactional
-// transfer between balances.
-func ExampleSTM_apply() {
-	cli, err := clientv3.New(clientv3.Config{Endpoints: endpoints})
-	if err != nil {
-		log.Fatal(err)
-	}
-	defer cli.Close()
-
-	// set up "accounts"
-	totalAccounts := 5
-	for i := 0; i < totalAccounts; i++ {
-		k := fmt.Sprintf("accts/%d", i)
-		if _, err = cli.Put(context.TODO(), k, "100"); err != nil {
-			log.Fatal(err)
-		}
-	}
-
-	exchange := func(stm concurrency.STM) error {
-		from, to := rand.Intn(totalAccounts), rand.Intn(totalAccounts)
-		if from == to {
-			// nothing to do
-			return nil
-		}
-		// read values
-		fromK, toK := fmt.Sprintf("accts/%d", from), fmt.Sprintf("accts/%d", to)
-		fromV, toV := stm.Get(fromK), stm.Get(toK)
-		fromInt, toInt := 0, 0
-		fmt.Sscanf(fromV, "%d", &fromInt)
-		fmt.Sscanf(toV, "%d", &toInt)
-
-		// transfer amount
-		xfer := fromInt / 2
-		fromInt, toInt = fromInt-xfer, toInt+xfer
-
-		// write back
-		stm.Put(fromK, fmt.Sprintf("%d", fromInt))
-		stm.Put(toK, fmt.Sprintf("%d", toInt))
-		return nil
-	}
-
-	// concurrently exchange values between accounts
-	var wg sync.WaitGroup
-	wg.Add(10)
-	for i := 0; i < 10; i++ {
-		go func() {
-			defer wg.Done()
-			if _, serr := concurrency.NewSTM(cli, exchange); serr != nil {
-				log.Fatal(serr)
-			}
-		}()
-	}
-	wg.Wait()
-
-	// confirm account sum matches sum from beginning.
-	sum := 0
-	accts, err := cli.Get(context.TODO(), "accts/", clientv3.WithPrefix())
-	if err != nil {
-		log.Fatal(err)
-	}
-	for _, kv := range accts.Kvs {
-		v := 0
-		fmt.Sscanf(string(kv.Value), "%d", &v)
-		sum += v
-	}
-
-	fmt.Println("account sum is", sum)
-	// Output:
-	// account sum is 500
-}