Remove use of String(byte[]) and String(byte[], int, int) constructors in engine 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.derby.catalog.SystemProcedures

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