tests: fix service test for ubuntu (#4174)

services/ubuntu/ubuntu.tester.js

 'use strict'
 
-const {
-  isVPlusDottedVersionNClausesWithOptionalSuffixAndEpoch,
-} = require('../test-validators')
+const Joi = require('@hapi/joi')
 const t = (module.exports = require('../tester').createServiceTester())
 
+const isUbuntuVersion = Joi.string().regex(
+  /^v(\d+:)?\d+(\.\d+)*([\w\\.]*)?([-+~].*)?$/
+)
+
 t.create('Ubuntu package (default distribution, valid)')
   .get('/apt.json')
   .expectBadge({
     label: 'ubuntu',
-    message: isVPlusDottedVersionNClausesWithOptionalSuffixAndEpoch,
+    message: isUbuntuVersion,
   })
 
 t.create('Ubuntu package (valid)')