Use QEMU's standard VGA instead of virtio-vga

On Arch, -vga virtio needs qemu-hw-display-virtio-vga and also
qemu-hw-display-virtio-gpu, which that package doesn't depend on; with only
the first, QEMU segfaults at start without a message. The smoketest's VMs
are headless (or VNC), so -vga std, which qemu-base has, is enough. This
reverts 2207208's extra package and checks.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/smoketest.bats

@@ -18,8 +18,7 @@ setup() {
   git -C "$WC" rev-parse HEAD > "$STATE/images/installed.ref"
 
   # A VM is a sleep that lets go of bats' output pipes
-  stub qemu-system-x86_64 '[ "$*" = "-device help" ] && { echo "name \"virtio-vga\", bus PCI"; exit; }
-    while [ $# -gt 0 ]; do [ "$1" = -pidfile ] && pidfile="$2"; shift; done
+  stub qemu-system-x86_64 'while [ $# -gt 0 ]; do [ "$1" = -pidfile ] && pidfile="$2"; shift; done
     /usr/bin/sleep 300 > /dev/null 2>&1 3>&- &
     echo $! > "$pidfile"'
   stub qemu-img 'touch "${@: -1}"'
@@ -99,16 +98,7 @@ last_run() {
   run cdd smoketest run 10 nosuch
   [ "$status" -eq 1 ]
   [[ "$output" == *"No scenario called nosuch"* ]]
-  # Only the check for the virtio-vga display, no VM
-  [ -z "$(grep '^qemu-system-x86_64 ' "$STUB_LOG" | grep -v -- '-device help')" ]
-}
-
-@test "run stops before any VM when QEMU has no virtio-vga display" {
-  stub qemu-system-x86_64 'echo "name \"VGA\", bus PCI"'
-  run cdd smoketest run 10
-  [ "$status" -eq 1 ]
-  [[ "$output" == *"QEMU has no virtio-vga display"* ]]
-  [ "$(grep -c '^qemu-system-x86_64 ' "$STUB_LOG")" -eq 1 ]
+  not_called qemu-system-x86_64
 }
 
 @test "each variant runs in its own VM" {
@@ -116,7 +106,7 @@ last_run() {
   [ "$status" -eq 0 ]
   [[ "$output" == *"PASS  30-variants @ one"* ]]
   [[ "$output" == *"PASS  30-variants @ two"* ]]
-  [ "$(grep '^qemu-system-x86_64 ' "$STUB_LOG" | grep -vc -- '-device help')" -eq 2 ]
+  [ "$(grep -c '^qemu-system-x86_64 ' "$STUB_LOG")" -eq 2 ]
   grep -q "variant two" "$(last_run)/30-variants@two/scenario.log"
 }