ci: add kernel-crash-dumps checks and examples

- Add an example kernel-crash-dumps section to the most-options.yaml
  example file and check the curthook is updated correctly.

- Add a check in the autoinstall-simple case that asserts the default
  value for the kernel-crash-dumps curthook config.

examples/autoinstall/most-options.yaml

@@ -69,3 +69,5 @@ storage:
   - {type: format, fstype: ext4, volume: raid-system, preserve: false, id: format-system}
   - {type: mount, device: format-system, path: /, id: mount-system}
   - {type: mount, device: format-boot, path: /boot, id: mount-boot, options: 'errors=remount-ro'}
+kernel-crash-dumps:
+  enabled: false

scripts/runtests.sh

@@ -171,6 +171,8 @@ python3 scripts/check-yaml-fields.py <(python3 scripts/check-yaml-fields.py $tmp
         timezone='"Pacific/Guam"' \
         ubuntu_advantage.token='"C1NWcZTHLteJXGVMM6YhvHDpGrhyy7"' \
         'snap.commands=[snap install --channel=3.2/stable etcd]'
+python3 scripts/check-yaml-fields.py "$tmpdir"/var/log/installer/curtin-install/subiquity-curthooks.conf \
+        kernel-crash-dumps.enabled=false
 grep -q 'finish: subiquity/Install/install/postinstall/install_package1: SUCCESS: installing package1' \
      $tmpdir/subiquity-server-debug.log
 grep -q 'finish: subiquity/Install/install/postinstall/install_package2: SUCCESS: installing package2' \
@@ -193,6 +195,8 @@ validate
 python3 scripts/check-yaml-fields.py "$tmpdir"/var/log/installer/autoinstall-user-data \
         'autoinstall.source.id="ubuntu-server-minimal"'
 grep -q 'finish: subiquity/Install/install/postinstall/run_unattended_upgrades: SUCCESS: downloading and installing security updates' $tmpdir/subiquity-server-debug.log
+python3 scripts/check-yaml-fields.py "$tmpdir"/var/log/installer/curtin-install/subiquity-curthooks.conf \
+        kernel-crash-dumps.enabled=null
 
 clean
 testname=autoinstall-hybrid