Close server socket and cleanups in test/jdk/javax/naming/module/RunBasic.java

When the test fails sometimes the output is truncated, or even absent, as the test's sub-process does not complete. This may happen if the client-side encounters an issue and leaves the non-daemon server-side thread blocked in accept. The test should close the server socket when the client-side completes. This will enable the "real" error to be seen.