Fix default Ci config path

When the ci config file it is set to an empty string

This MR adds a blank check to handle the empty string filename

Changelog: fixed

lib/security/ci_configuration/base_build_action.rb

@@ -6,7 +6,7 @@ module Security
       def initialize(auto_devops_enabled, existing_gitlab_ci_content, ci_config_path = ::Ci::Pipeline::DEFAULT_CONFIG_PATH)
         @auto_devops_enabled = auto_devops_enabled
         @existing_gitlab_ci_content = existing_gitlab_ci_content || {}
-        @ci_config_path = ci_config_path || ::Ci::Pipeline::DEFAULT_CONFIG_PATH
+        @ci_config_path = ci_config_path.presence || ::Ci::Pipeline::DEFAULT_CONFIG_PATH
       end
 
       def generate

spec/lib/security/ci_configuration/sast_iac_build_action_spec.rb

@@ -7,6 +7,7 @@ RSpec.describe Security::CiConfiguration::SastIacBuildAction do
 
   let(:params) { {} }
 
+  shared_examples 'existing .gitlab-ci.yml tests' do
     context 'with existing .gitlab-ci.yml' do
       let(:auto_devops_enabled) { false }
 
@@ -104,6 +105,19 @@ RSpec.describe Security::CiConfiguration::SastIacBuildAction do
         end
       end
     end
+  end
+
+  context 'with existing .gitlab-ci.yml and when the ci config file configuration was not set' do
+    subject(:result) { described_class.new(auto_devops_enabled, gitlab_ci_content).generate }
+
+    it_behaves_like 'existing .gitlab-ci.yml tests'
+  end
+
+  context 'with existing .gitlab-ci.yml and when the ci config file configuration was deleted' do
+    subject(:result) { described_class.new(auto_devops_enabled, gitlab_ci_content, ci_config_path: '').generate }
+
+    it_behaves_like 'existing .gitlab-ci.yml tests'
+  end
 
   context 'with no .gitlab-ci.yml' do
     let(:gitlab_ci_content) { nil }