Precondition: import the template from zbx_export_templates.yaml

Steps to reproduce:

1. Open template "test" items
2. Select Tag1
3. Check displayed items and Tag2 and Tag3 numbers in subfilter

Result: Tag1 is common for all items. Subfilter counter values next to Tag2 and Tag3 are incorrect. See the gif attachment:

Expected: As mentioned in the comment ZBX-20505, the "old" subfilter format in items should be replaced with the new one.

Note: the same issue appears in other places where the subfilter is used, like Configuration>Hosts>Host items. Please take it into account.