Disk health indicator doesn't take into account watermark.low/high.max_headroom

[fcofdez]

In #88639 we introduced a new setting that allows configuring a maximum headroom in disk watermarks that helps reducing the waste of disk space in large disks. The disk health indicator should take that new setting into account to avoid reporting issues when there's still room for new data in the cluster.

elasticsearch/server/src/main/java/org/elasticsearch/health/metadata/HealthMetadata.java

Lines 193 to 199 in 6ec31ed

	public ByteSizeValue getFreeBytesHighWatermark(ByteSizeValue total) {
	return getFreeBytes(total, highWatermark, ByteSizeValue.MINUS_ONE);
	}
	public ByteSizeValue getFreeBytesFloodStageWatermark(ByteSizeValue total) {
	return getFreeBytes(total, floodStageWatermark, ByteSizeValue.MINUS_ONE);
	}

Those calls should take into account the available max headroom.