Incorrect processing of deleted sns nodes

After the deletion of several SNS nodes, autoexport engine creates the following statements in yaml:

config:
/sns[1]:
.meta:delete: true
/sns[2]:
.meta:delete: true

Although this is valid syntax, the processing order of deleted items in ConfigurationTreeBuilder should be changed in a way that sns nodes with highest index should be deleted first.

Current behavior makes it so, that if sns nodes with lower indexes getting deleted first, then deletion of nodes with highest indexes is skipped and thus, it makes ConfigurationModelImpl invalid(since for e.g. sns[2] node will not be deleted). It also breaks current mechanism of restoration of deleted upstream nodes.