Catch YAML errors when parsing security policies

Changelog: fixed
EE: true

doc/user/application_security/policies/index.md

@@ -357,7 +357,7 @@ scan_execution_policy:
   - type: schedule
     branches:
     - main
-    cadence: */10 * * * *
+    cadence: "*/10 * * * *"
   actions:
   - scan: dast
     scanner_profile: Scanner Profile C
@@ -378,7 +378,7 @@ scan_execution_policy:
   enabled: true
   rules:
   - type: schedule
-    cadence: '15 3 * * *'
+    cadence: "15 3 * * *
     clusters:
       production-cluster:
         containers:

ee/app/models/security/orchestration_policy_configuration.rb

@@ -35,6 +35,8 @@ module Security
 
         Gitlab::Config::Loader::Yaml.new(policy_blob).load!
       end
+    rescue Gitlab::Config::Loader::FormatError
+      nil
     end
 
     def policy_configuration_exists?

ee/spec/models/security/orchestration_policy_configuration_spec.rb

@@ -102,6 +102,14 @@ RSpec.describe Security::OrchestrationPolicyConfiguration do
       it { expect(subject.dig(:scan_execution_policy, 0, :name)).to eq('Run DAST in every pipeline') }
     end
 
+    context 'when policy has invalid YAML format' do
+      let(:policy_yaml) do
+        'cadence: * 1 2 3'
+      end
+
+      it { expect(subject).to be_nil }
+    end
+
     context 'when policy is nil' do
       let(:policy_yaml) { nil }