Fix rpm and deb package name format

[Smjert]

By using RPM-DEFAULT and DEB-DEFAULT as package names,
CPack leaves the naming of the packages to the underlying
packaging tools which will use the standard naming format.

Fixes #6074

[theopolis]

Wow! Good find!

[Smjert]

Wow! Good find!

Yeah it was in the CMake docs afterall: https://cmake.org/cmake/help/v3.17/cpack_gen/rpm.html#variable:CPACK_RPM_%3Ccomponent%3E_FILE_NAME

This may be set to RPM-DEFAULT to allow rpmbuild tool to generate package file name by itself. Alternatively provided package file name must end with .rpm suffix.

and

https://cmake.org/cmake/help/v3.17/cpack_gen/deb.html?highlight=cpack%20deb#variable:CPACK_DEBIAN_%3CCOMPONENT%3E_FILE_NAME

This may be set to DEB-DEFAULT to allow the CPack DEB generator to generate package file name by itself in deb format:

<PackageName>_<VersionNumber>-<DebianRevisionNumber>_<DebianArchitecture>.deb

But I didn't notice until now ^^'
Although it doesn't mention the ddeb case, the result seemed the correct one.