Fix gosimple S1005 linting issue (#8870)
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
```
```
