Mark WMTSServiceTest.testDefaultStyleRequired as online
Description
During verification of https://github.com/geotools/geotools/pull/2032 and with similar local testing, there was an intermittent failure of one test, which is reaching out to a public server that is not part of OSGEO.
Torben notes: ... then it should be marked as online and include an "assume" check for connectivity
Environment
None
