runners: Fix tarball build for zfs-qemu-packages workflow

[tonyhutter]

Motivation and Context

Fix tarball creation in the zfs-qemu-packages github runner.

Description

The initial release tarballs we built for for zfs-2.3.1 were incorrect since they did not have a ./configure script, and their files were not in a top level zfs-2.3.1/ directory. This commit builds the tarballs in the same way we built them on buildbot so their contents are as expected.

How Has This Been Tested?

Built tarball via zfs-qemu-packages and observed contents.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.

[tonyhutter]

@mcmilk could you take a look at this one when you get a chance?