smoketest: don't run the pre-push hook when pushing to the VM

upstream_set pushes the commit under test from the working copy, so
coredesktop-dev's pre-push hook ran make check on every push to the VM.
Inside the smoketest those checks saw VM_GIT_URL and friends, the
smoketest tests pushed to the real VM and failed, and the hook stopped
the push, failing the installed image's build. The push now uses
--no-verify, and the tests clear the smoketest's variables.

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

tests/smoketest.bats

@@ -44,6 +44,13 @@ upstream_main() {
   [ "$(upstream_main)" = "$V2" ]
 }
 
+@test "pushing to the VM skips the working copy's pre-push hook" {
+  printf '%s\n' '#!/bin/bash' 'echo hook ran; exit 1' > "$SMOKETEST_REPO/.git/hooks/pre-push"
+  chmod +x "$SMOKETEST_REPO/.git/hooks/pre-push"
+  smoketest_prepare
+  [ "$(upstream_main)" = "$V2" ]
+}
+
 @test "prepare sends CoreDesktop's URLs to the fake upstream" {
   smoketest_prepare
   for url in "${COREDESKTOP_URLS[@]}"; do