Enforce quota checks after crawl (#10036)

Enforce bucket quotas when crawling has finished. 
This ensures that we will not do quota enforcement on old data.

Additionally, delete less if we are closer to quota than we thought.

cmd/data-usage-cache.go

@@ -335,6 +335,21 @@ func (d *dataUsageCache) bucketsUsageInfo(buckets []BucketInfo) map[string]Bucke
 	return dst
 }
 
+// bucketUsageInfo returns the buckets usage info.
+// If not found all values returned are zero values.
+func (d *dataUsageCache) bucketUsageInfo(bucket string) BucketUsageInfo {
+	e := d.find(bucket)
+	if e == nil {
+		return BucketUsageInfo{}
+	}
+	flat := d.flatten(*e)
+	return BucketUsageInfo{
+		Size:                 uint64(flat.Size),
+		ObjectsCount:         uint64(flat.Objects),
+		ObjectSizesHistogram: flat.ObjSizes.toMap(),
+	}
+}
+
 // sizeRecursive returns the path as a flattened entry.
 func (d *dataUsageCache) sizeRecursive(path string) *dataUsageEntry {
 	root := d.find(path)