Refactor java/net/URLConnection/UNCTest.sh java/net/URLConnection/6212146/Test.sh to remove shell dependency

java/net/URLConnection/UNCTest.java

The shell file involves the selection of the os to run the test. As UNCTest should be run only in windows the shell code has the logic to run in it.
The proposed refactor is the use @OS tag in jtreg and remove the shell file.


java/net/URLConnection/6212146/Test.java

The test invloves creating a jar file with a class but test incorrectly referring to the file in jar expecting ZipException for failure.
The proposed refactor is to remove having a static jar file in the source base and shell. The test is re-wriiten to use test libaray utils to create the jar on the fly placed in the scratch directory.