ADAPRF to obtain default dbid from ADALNK

A pre-fetch command did not go to the correct ADABAS nucleus because ADAPRF used the original default dbid in ADALNK. Change ADALNK to dynamically to specify the default.

Currently ADAPRF saves that original dbid and uses it for all commands it issues. With this enhancement, ADAPRF would get the default dbid directly from ADALNK for every command it issues

This is Special Purpose zap AY743103/AY814120

This is R&D Requirement number: 1881