8215244: jdk/jshell/ToolBasicTest.java testHistoryReference failed

Mark history entries from previous sessions with timestamp that is definitelly in the past.

Reviewed-by: rfield

src/jdk.jshell/share/classes/jdk/internal/jshell/tool/ConsoleIOContext.java

@@ -185,7 +185,7 @@ class ConsoleIOContext extends IOContext {
             it.set(current);
         }
 
-        historyLoad = Instant.now();
+        historyLoad = Instant.MIN;
         loadHistory.forEach(line -> reader.getHistory().add(historyLoad, line));
 
         in = reader;