profiler: Delete stack in batches

[kakkoyun]

// Delete all stacks.
//
// The capacity will be difficult to estimate without counting as it's
// likely that there will be more than we need due to duplicated stack IDs.
keysToDelete := make([]int32, 0, len(stacksKeys))
for key := range stacksKeys {
	keysToDelete = append(keysToDelete, key)
}

// TODO(javierhonduco): Getting -ENOTSUPP, perhaps my kernel doesn't support it?
// Needs more investigation.
//
processed, err := p.bpfMaps.stacks.DeleteKeyBatch(unsafe.Pointer(&keysToDelete[0]), uint32(len(keysToDelete)))
level.Debug(p.logger).Log("msg", "deleted counts map in batch", "deleted", processed)
if err != nil {
	    return fmt.Errorf("failed to delete stacks in batch: %w", err)
}

cc @javierhonduco

ref #602 and #395

[javierhonduco]

// TODO(javierhonduco): Getting -ENOTSUPP, perhaps my kernel doesn't support it?

Oh yes, I remember this, was quite odd. Can take a look in some weeks.

Wondering how hotDeleteKeyBatch is, would be interesting to perhaps check our own profiles in the demo cluster