machineConfigure.mk changes it's encdoing while copying files from Source to Dest with Java21 on z/OS

machineConfigure.mk changes it's encdoing while copying files from Source to Dest with Java21. The copy task is writing contents of makefiles in UTF-8 for Java21, which is causing the failure. https://github.com/adoptium/TKG/pull/671 ( removing ENV variable -Dfile.encoding=IBM-1047) exposed this issue.

Start with machineConfigure.mk and inspect the copy task when running Java 21 on z/OS, using the issue description and PR #671 for context. Verify how file encoding is selected during the Source-to-Dest copy. Done means makefiles retain the required encoding and the Java 21 z/OS failure is prevented.

Written by the indexing model from the issue text.