ws: Fix updating gettext files
ws: Fix updating gettext files

Commit dab20ffefe6 broke updating/uploading/downloading PO files:

    cp src/ws/cockpit.appdata.xml.in .
    /bin/intltool-extract -l --type=gettext/xml cockpit.appdata.xml.in
    Wrote ./tmp/cockpit.appdata.xml.in.h
    cp  .
    cp: missing destination file operand after '.'
    Try 'cp --help' for more information.
    make: *** [Makefile:9906: prepare-po-desktop] Error 1

Clean up the desktop file leftovers in the Makefile to fix that.

Closes #10714
andreasn/cockpit,moraleslazaro/cockpit,deryni/cockpit,deryni/cockpit,garrett/cockpit,andreasn/cockpit,cockpit-project/cockpit,andreasn/cockpit,cockpit-project/cockpit,mvollmer/cockpit,cockpituous/cockpit,cockpit-project/cockpit,deryni/cockpit,martinpitt/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,martinpitt/cockpit,deryni/cockpit,moraleslazaro/cockpit,andreasn/cockpit,cockpituous/cockpit,garrett/cockpit,garrett/cockpit,garrett/cockpit,cockpit-project/cockpit,andreasn/cockpit,mvollmer/cockpit,martinpitt/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,deryni/cockpit,mvollmer/cockpit,deryni/cockpit,andreasn/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,garrett/cockpit,cockpituous/cockpit,andreasn/cockpit,deryni/cockpit,cockpit-project/cockpit,martinpitt/cockpit,cockpituous/cockpit,moraleslazaro/cockpit