testing/libguestfs: upgrade to 1.44.1

This upgrade is required for compilation with OCaml 4.12 that is now included in edge.

The python 3.8 patch has been reverted as it doesn't apply and the build appears to succeed without it - we're also on python 3.9.

I've included a new patch that ensures that everything compiles correctly even if --disable-ocaml is selected, I'll try and get this accepted upstream soon.

Additionally removed an unused variable and removed $pkgname from the download string to satisfy the linter.