Remove use of String(byte[]) and String(byte[], int, int) constructors in testing leading to non-portable behaviour

These constructors use the Java default platform encoding to convert the bytes to a String, this typically leads to bugs on platforms with different encodings.

Replace with code using fixed conversion, or alternative mechanisms.
If the call is required its use should be commented as to why it is required.

org.apache.derbyTesting.functionTests.tests.jdbcapi.blobclob4BLOB
org.apache.derbyTesting.functionTests.tests.jdbcapi.resultset
org.apache.derbyTesting.functionTests.tests.lang.coalesceTests
org.apache.derbyTesting.functionTests.tests.store.streamingColumn

I generated this list using the Java search in eclipse for references to the constructors
String(byte[])
String(byte[],int,int) (no occurrences in java/testing)