[BUG] 指标文件读取方法不正确

[brucelwl]

Sentinel/sentinel-core/src/main/java/com/alibaba/csp/sentinel/node/metric/MetricSearcher.java

Lines 208 to 211 in 195150b

	while ((second = indexIn.readLong()) < beginSecond) {
	offset = indexIn.readLong();
	lastPosition.offsetInIndex = in.getChannel().position();
	}

209行 offset = indexIn.readLong(); 不应该写, 应该剔除这行, 这样会导致读取的数据不正确

假如读取的是 1729965161000L的数据, 返回的是1729965162000L及之后的数据,
但如果1729965161000L是文件的最后一个时间的记录数据, 又会被读取到

List<MetricNode> metricNodes = searcher.find(1729965161000L, 5);

[manojks1999]

@brucelwl , I have made a PR please have a look and let me know if any changes are required.

Thanks

[brucelwl]

@manojks1999 看着没什么问题