Fix gosimple S1005 linting issue

Results before change
```
⇶  golangci-lint run ./... --disable-all --enable=gosimple | grep 1005
fix/fixer_comm_config.go:48:4: S1005: should write `sshHostPortMinRaw := builders["ssh_host_port_min"]` instead of `sshHostPortMinRaw, _ := builders["ssh_host_port_min"]` (gosimple)
fix/fixer_comm_config.go:64:4: S1005: should write `sshHostPortMaxRaw := builders["ssh_host_port_max"]` instead of `sshHostPortMaxRaw, _ := builders["ssh_host_port_max"]` (gosimple)
fix/fixer_comm_config.go:81:4: S1005: should write `sshSkipNatMappingRaw := builders["ssh_skip_nat_mapping"]` instead of `sshSkipNatMappingRaw, _ := builders["ssh_skip_nat_mapping"]` (gosimple)
packer/artifact_mock.go:47:2: S1005: should write `value := a.StateValues[name]` instead of `value, _ := a.StateValues[name]` (gosimple)
packer/artifact_test.go:31:2: S1005: should write `value := a.state[name]` instead of `value, _ := a.state[name]` (gosimple)
```

Results after change
```
```

builder/alicloud/ecs/image_config.go

@@ -205,7 +205,7 @@ func (c *AlicloudImageConfig) Prepare(ctx *interpolate.Context) []error {
 		strings.HasPrefix(c.AlicloudImageName, "https://") {
 		errs = append(errs, fmt.Errorf("image_name can't start with 'http://' or 'https://'"))
 	}
-	reg := regexp.MustCompile(`\s+`)
+	reg := regexp.MustCompile("\\s+")
 	if reg.FindString(c.AlicloudImageName) != "" {
 		errs = append(errs, fmt.Errorf("image_name can't include spaces"))
 	}

builder/amazon/ebs/builder_acc_test.go

@@ -87,14 +87,6 @@ func TestBuilderAcc_forceDeleteSnapshot(t *testing.T) {
 	})
 }
 
-func TestBuilderAcc_testSourceAmiFilter(t *testing.T) {
-	builderT.Test(t, builderT.TestCase{
-		PreCheck: func() { testAccPreCheck(t) },
-		Builder:  &Builder{},
-		Template: testSourceAmiFilter,
-	})
-}
-
 func checkSnapshotsDeleted(snapshotIds []*string) builderT.TestCheckFunc {
 	return func(artifacts []packer.Artifact) error {
 		// Verify the snapshots are gone
@@ -352,29 +344,6 @@ const testBuilderAccEncrypted = `
 }
 `
 
-const testSourceAmiFilter = `
-{
-	"builders": [{
-        "type": "test",
-        "ami_name": "packer-filter-test-{{timestamp}}",
-        "region": "us-east-1",
-        "instance_type": "t2.micro",
-        "ssh_username": "ubuntu",
-        "source_ami_filter": {
-            "filters": {
-                "name": "*ubuntu-xenial-16.04-amd64-server-*",
-                "root-device-type": "ebs",
-                "virtualization-type": "hvm"
-            },
-            "most_recent": true,
-            "owners": [
-                "099720109477"
-            ]
-        }
-    }]
-}
-`
-
 func buildForceDeregisterConfig(val, name string) string {
 	return fmt.Sprintf(testBuilderAccForceDeregister, val, name)
 }

builder/azure/arm/config.go

@@ -55,12 +55,12 @@ const (
 )
 
 var (
-	reCaptureContainerName = regexp.MustCompile(`^[a-z0-9][a-z0-9\-]{2,62}$`)
-	reCaptureNamePrefix    = regexp.MustCompile(`^[A-Za-z0-9][A-Za-z0-9_\-\.]{0,23}$`)
+	reCaptureContainerName = regexp.MustCompile("^[a-z0-9][a-z0-9\\-]{2,62}$")
+	reCaptureNamePrefix    = regexp.MustCompile("^[A-Za-z0-9][A-Za-z0-9_\\-\\.]{0,23}$")
 	reManagedDiskName      = regexp.MustCompile(validManagedDiskName)
 	reResourceGroupName    = regexp.MustCompile(validResourceGroupNameRe)
-	reSnapshotName         = regexp.MustCompile(`^[A-Za-z0-9_]{1,79}$`)
-	reSnapshotPrefix       = regexp.MustCompile(`^[A-Za-z0-9_]{1,59}$`)
+	reSnapshotName         = regexp.MustCompile("^[A-Za-z0-9_]{1,79}$")
+	reSnapshotPrefix       = regexp.MustCompile("^[A-Za-z0-9_]{1,59}$")
 )
 
 type PlanInformation struct {

builder/qemu/driver.go

@@ -189,7 +189,7 @@ func (d *QemuDriver) Version() (string, error) {
 
 	versionOutput := strings.TrimSpace(stdout.String())
 	log.Printf("Qemu --version output: %s", versionOutput)
-	versionRe := regexp.MustCompile(`[\.[0-9]+]*`)
+	versionRe := regexp.MustCompile("[\\.[0-9]+]*")
 	matches := versionRe.FindStringSubmatch(versionOutput)
 	if len(matches) == 0 {
 		return "", fmt.Errorf("No version found: %s", versionOutput)