no longer using blank string for failed regex

src/utilities/workflowAnnotationUtils.test.ts

@@ -18,7 +18,7 @@ describe('WorkflowAnnotationUtils', () => {
       })
       it('should return a blank string when regex fails (https://github.com/Azure/k8s-deploy/issues/266)', () => {
          const label = '持续部署'
-         expect(cleanLabel(label)).toEqual('')
+         expect(cleanLabel(label)).toEqual('github-workflow-file')
 
          let removedInvalidChars = label
             .replace(/\s/gi, '_')

src/utilities/workflowAnnotationUtils.ts

@@ -43,6 +43,8 @@ export function cleanLabel(label: string): string {
       .replace(/[^-A-Za-z0-9_.]/gi, '')
 
    const regex = /([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9]/
-   const regexResult = regex.exec(removedInvalidChars) || ['']
+   const regexResult = regex.exec(removedInvalidChars) || [
+      'github-workflow-file'
+   ]
    return regexResult[0]
 }