Replace non-public TabletClosedException and ScanTimedOutException

[SethSmucker]

Summary

• Replace instanceof TabletClosedException with class name check
• Replace catch (ScanTimedOutException) with class name check inside generic catch block

Files Changed

• QueryIterator.java - TabletClosedException
• DocIdQueryIterator.java - TabletClosedException
• DocumentIterator.java - TabletClosedException
• Scan.java - ScanTimedOutException

Approach

Since these are non-public Accumulo classes that won't exist in Accumulo 4, we use class name comparison:

private static boolean isTabletClosedException(Throwable t) {
    return t != null && t.getClass().getName().equals(
        "org.apache.accumulo.tserver.tablet.TabletClosedException");
}

Fixes #3317
Part of #2443

[foster33]

Should we be returning this here? Just curious because it was not in the original catch block you removed