[Security Solution] Fix bulk edit rules tests (elastic#164692)

**Relates to:** elastic#161507

## Summary

This PR fixes **bulk_edit_rules.cy.ts** flakiness found while running Security Solution Cypress tests in Flaky test runner ([run 1](https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/2969) and [run 2](https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/2970)).

## Flaky test runner

[bulk_edit_rules.cy.ts 300 runs](https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/2975) 🟢

(cherry picked from commit 6ab3aa3)

x-pack/test/security_solution_cypress/cypress/e2e/detection_response/rule_management/rule_actions/bulk_actions/bulk_edit_rules.cy.ts

@@ -96,6 +96,7 @@ import {
 import {
   createAndInstallMockedPrebuiltRules,
   getAvailablePrebuiltRulesCount,
+  preventPrebuiltRulesPackageInstallation,
 } from '../../../../../tasks/api_calls/prebuilt_rules';
 import { setRowsPerPageTo, sortByTableColumn } from '../../../../../tasks/table_pagination';
 
@@ -123,6 +124,7 @@ describe('Detection rules, bulk edit', { tags: [tag.ESS, tag.BROKEN_IN_SERVERLES
     // Make sure persisted rules table state is cleared
     resetRulesTableState();
     deleteAlertsAndRules();
+    preventPrebuiltRulesPackageInstallation(); // Make sure prebuilt rules aren't pulled from Fleet API
     cy.task('esArchiverResetKibana');
     createRule(getNewRule({ name: RULE_NAME, ...defaultRuleData, rule_id: '1', enabled: false }));
     createRule(
@@ -233,9 +235,7 @@ describe('Detection rules, bulk edit', { tags: [tag.ESS, tag.BROKEN_IN_SERVERLES
         clickAddTagsMenuItem();
         waitForMixedRulesBulkEditModal(rows.length);
 
-        getAvailablePrebuiltRulesCount().then((availablePrebuiltRulesCount) => {
-          checkPrebuiltRulesCannotBeModified(availablePrebuiltRulesCount);
-        });
+        checkPrebuiltRulesCannotBeModified(PREBUILT_RULES.length);
 
         // user cancels action and modal disappears
         cancelConfirmationModal();