Remove runner "locked" toggle where not used

This change removes the "locked" checkbox for runners that cannot be
locked.

Previously the locked checkbox was disabled where it didn't apply, with
this change the "locked" is not available at all.

Changelog: changed

app/assets/javascripts/runner/components/runner_update_form.vue

@@ -135,9 +135,9 @@ export default {
     </gl-form-checkbox>
 
     <gl-form-checkbox
+      v-if="canBeLockedToProject"
       v-model="model.locked"
       data-testid="runner-field-locked"
-      :disabled="!canBeLockedToProject"
     >
       {{ __('Lock to current projects') }}
       <template #help>

spec/frontend/runner/components/runner_update_form_spec.js

@@ -54,7 +54,7 @@ describe('RunnerUpdateForm', () => {
       ? ACCESS_LEVEL_REF_PROTECTED
       : ACCESS_LEVEL_NOT_PROTECTED,
     runUntagged: findRunUntaggedCheckbox().element.checked,
-    locked: findLockedCheckbox().element.checked,
+    locked: findLockedCheckbox().element?.checked || false,
     ipAddress: findIpInput().element.value,
     maximumTimeout: findMaxJobTimeoutInput().element.value || null,
     tagList: findTagsInput().element.value.split(',').filter(Boolean),
@@ -153,15 +153,15 @@ describe('RunnerUpdateForm', () => {
   });
 
   it.each`
-    runnerType       | attrDisabled  | outcome
-    ${INSTANCE_TYPE} | ${'disabled'} | ${'disabled'}
-    ${GROUP_TYPE}    | ${'disabled'} | ${'disabled'}
-    ${PROJECT_TYPE}  | ${undefined}  | ${'enabled'}
-  `(`When runner is $runnerType, locked field is $outcome`, ({ runnerType, attrDisabled }) => {
+    runnerType       | exists   | outcome
+    ${INSTANCE_TYPE} | ${false} | ${'hidden'}
+    ${GROUP_TYPE}    | ${false} | ${'hidden'}
+    ${PROJECT_TYPE}  | ${true}  | ${'shown'}
+  `(`When runner is $runnerType, locked field is $outcome`, ({ runnerType, exists }) => {
     const runner = { ...mockRunner, runnerType };
     createComponent({ props: { runner } });
 
-    expect(findLockedCheckbox().attributes('disabled')).toBe(attrDisabled);
+    expect(findLockedCheckbox().exists()).toBe(exists);
   });
 
   describe('On submit, runner gets updated', () => {