[test] Serialization WritePrimitive test revised for readFully test fails

The test added to jdk/java/io/Serializable/OldTests/WritePrimitive.java fails with:

Regression test for testing of serialization/deserialization of primitives

TEST FAILED: java.io.EOFException
at java.base/java.io.ObjectInputStream$BlockDataInputStream.readByte(ObjectInputStream.java:3376)
at java.base/java.io.ObjectInputStream$BlockDataInputStream.readUTFChar(ObjectInputStream.java:3768)
at java.base/java.io.ObjectInputStream$BlockDataInputStream.readUTFBody(ObjectInputStream.java:3678)
at java.base/java.io.ObjectInputStream$BlockDataInputStream.readUTF(ObjectInputStream.java:3474)
at java.base/java.io.ObjectInputStream.readUTF(ObjectInputStream.java:1248)
at WritePrimitive.main(WritePrimitive.java:94)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.base/java.lang.reflect.Method.invoke(Method.java:577)
at com.sun.javatest.regtest.agent.MainActionHelper$AgentVMRunnable.run(MainActionHelper.java:312)
at java.base/java.lang.Thread.run(Thread.java:833)

Bytes read: 68, Input remaining: 136
...