CV: skip sporadically failing template delivery

[mbien]

#7333 degrades CV test stability

• failure: "FSException: Cannot get shared access"
• tests can be brute forced into passing.
• It is not clear if something is wrong with the hint editor support or if this template is just degrading the sporadically failing tests further due to changed timing.

lets try to skip over it and check if it improves the stability.

other:

• wrap masterfs.macosx in retry script due to sporadic failures in OSXNotifierTest#testNextEvent
• NbTestCase: use Files#delete for better exception on failure, (second commit)
  • "Cannot delete file" isn't very useful, Files#delete will state the cause if available
  • might help to debug some sporadic test failures
  • global refactoring to replace similar patterns resulted in some TestUtil cleanup which was duplicated everywhere

[mbien]

so the CV tests on linux passed on first attempt, which is a good sign (esp when compared to https://github.com/apache/netbeans/actions/runs/8876164558).

platform/masterfs.macosx (testNextEvent: org.netbeans.modules.masterfs.watcher.macosx.OSXNotifierTest) seems to fail often recently, but I can't help with that one due to lack of hardware + it isn't related to this problem. I might wrap it in the retry script.

[matthiasblaesing]

Of course a fix for the root cause of the instability would be preferred, but not causing false-positives is more important.
In general this looks like a good cleanup. Thank you!

[matthiasblaesing]

Thanks!