ci: fixing nvmf-tcp-vm-autotest by adding missing xxd

[glimchb]

will be moved to pkgdep.sh or autotest_setup.sh after merging to spdk/spdk is re-enabled

see spdk/spdk#3615 (comment)

[karlatec]

Even if it's temporary - why put it here?
https://github.com/spdk/spdk-ci/actions/workflows/build_qcow2.yml takes Gerrit refspec as an input argument, so we can build a new image with xxd package included even without merging the change.

[glimchb]

@karlatec because it is quicker and easier to move forward like this self contained
and then take all missing packages and add them to gerrit properly and review there

[karlatec]

I still suggest closing this one.
I already have a change https://review.spdk.io/c/spdk/spdk/+/25661 adding xxd to list of installed pacakges.

Once @tomzawadzki merges #28 we can build the qcow2 image with xxd installed (which is what I did on my fork here)

[karlatec]

New qcow2 image with xxd is here: https://github.com/spdk/spdk-ci/actions/runs/13562927805

[tomzawadzki]

No longer needed, upstream SPDK now contains xxd - spdk/spdk@d0bb354.