Remove `okio.use` and redundant length init.

Change-Id: Ibac659c7aff6d8be99f52d012d603f8251bbd23d

core/network/src/main/kotlin/com/google/samples/apps/nowinandroid/core/network/demo/DemoNiaNetworkDataSource.kt

@@ -29,7 +29,6 @@ import kotlinx.coroutines.withContext
 import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.json.Json
 import kotlinx.serialization.json.decodeFromStream
-import okio.use
 import java.io.ByteArrayOutputStream
 import java.io.InputStream
 import java.nio.charset.StandardCharsets
@@ -85,7 +84,7 @@ class DemoNiaNetworkDataSource @Inject constructor(
     ) {
         val result = ByteArrayOutputStream()
         val buffer = ByteArray(1024)
-        var length = 0
+        var length: Int
         while (true) {
             length = inputStream.read(buffer)
             if (length == -1) break