### What changes were proposed in this pull request?
`NettyMemoryMetrics` supports `numHeapArenas`, `numDirectArenas`, `tinyCacheSize`, `smallCacheSize`, `normalCacheSize`, `numThreadLocalCaches` and `chunkSize` from `PooledByteBufAllocatorMetric`. Meanwhile, remove `server_` prefix from metric name of netty memory metric in `monitoring.md`.
### Why are the changes needed?
`PooledByteBufAllocatorMetric` provides the following API to support netty memory metrics:
```
public int numHeapArenas() {
return this.allocator.numHeapArenas();
}
public int numDirectArenas() {
return this.allocator.numDirectArenas();
}
public List<PoolArenaMetric> heapArenas() {
return this.allocator.heapArenas();
}
public List<PoolArenaMetric> directArenas() {
return this.allocator.directArenas();
}
public int numThreadLocalCaches() {
return this.allocator.numThreadLocalCaches();
}
public int tinyCacheSize() {
return this.allocator.tinyCacheSize();
}
public int smallCacheSize() {
return this.allocator.smallCacheSize();
}
public int normalCacheSize() {
return this.allocator.normalCacheSize();
}
public int chunkSize() {
return this.allocator.chunkSize();
}
public long usedHeapMemory() {
return this.allocator.usedHeapMemory();
}
public long usedDirectMemory() {
return this.allocator.usedDirectMemory();
}
```
`NettyMemoryMetrics` only supports `usedHeapMemory` and `usedDirectMemory`, which could support `numHeapArenas`, `numDirectArenas`, `tinyCacheSize`, `smallCacheSize`, `normalCacheSize`, `numThreadLocalCaches` and `chunkSize` from `PooledByteBufAllocatorMetric`.
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
[Celeborn Grafana Dashboard](https://stenicholas.grafana.net/public-dashboards/a520ca36a33843a38bbde28387023f97)
Closes#2802 from SteNicholas/CELEBORN-1640.
Authored-by: SteNicholas <programgeek@163.com>
Signed-off-by: mingji <fengmingxiao.fmx@alibaba-inc.com>
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