Fix undefined method error in validate_remote_git_endpoint service

* update tests

Changelog: fixed

app/services/import/validate_remote_git_endpoint_service.rb

@@ -21,7 +21,7 @@ module Import
     def execute
       uri = Gitlab::Utils.parse_url(@params[:url])
 
-      return error("Invalid URL") unless uri
+      return ServiceResponse.error(message: "#{@params[:url]} is not a valid URL") unless uri
 
       uri.fragment = nil
       url = Gitlab::Utils.append_path(uri.to_s, "/info/refs?service=#{GIT_SERVICE_NAME}")

spec/services/import/validate_remote_git_endpoint_service_spec.rb

@@ -46,6 +46,14 @@ RSpec.describe Import::ValidateRemoteGitEndpointService do
         expect(result.message).to eq(error_message)
       end
 
+      it 'reports error when invalid URL is provided' do
+        result = described_class.new(url: 1).execute
+
+        expect(result).to be_a(ServiceResponse)
+        expect(result.error?).to be(true)
+        expect(result.message).to eq('1 is not a valid URL')
+      end
+
       it 'reports error when required header is missing' do
         stub_full_request(endpoint_url, method: :get).to_return(valid_response.merge({ headers: nil }))