##### SUMMARY
If you import a template with a xml/json file the linked templates of a templates ( so the child templates not the root ones ) aren't processed if you want to remove linked templates.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
zabbix_templates

##### ANSIBLE VERSION
```shell
ansible 2.9.2
  config file = /mnt/d/Code/gitlab/zabbix-servers/ansible/ansible.cfg
  configured module search path = ['/home/fism/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /mnt/d/Code/gitlab/zabbix-servers/venv/lib/python3.6/site-packages/ansible
  executable location = /mnt/d/Code/gitlab/zabbix-servers/venv/bin/ansible
  python version = 3.6.9 (default, Nov  7 2019, 10:44:02) [GCC 8.3.0]
```

##### OS / ENVIRONMENT
Zabbix 4.4.4 on RHEL7

##### STEPS TO REPRODUCE
Export a template (no matter if with Zabbix itself or ansible). Change the corresponding linked template section of a template and reimport it.

Exported with Zabbix:
```yaml
<zabbix_export>
    <version>4.4</version>
    <date>2020-01-23T13:25:32Z</date>
    <groups>
        <group>
            <name>Templates</name>
        </group>
    </groups>
    <templates>
        <template>
            <template>fisma</template>
            <name>fisma</name>
            <templates>
                <template>
                    <name>fismb</name>
                </template>
            </templates>
            <groups>
                <group>
                    <name>Templates</name>
                </group>
            </groups>
        </template>
    </templates>
</zabbix_export>
```

Change to this with removing all linked templates ( fismb in above example ).
```yaml
<zabbix_export>
    <version>4.4</version>
    <date>2020-01-23T13:25:32Z</date>
    <groups>
        <group>
            <name>Templates</name>
        </group>
    </groups>
    <templates>
        <template>
            <template>fisma</template>
            <name>fisma</name>
            <groups>
                <group>
                    <name>Templates</name>
                </group>
            </groups>
        </template>
    </templates>
</zabbix_export>
```

##### EXPECTED RESULTS
fismb should be unlinked from fisma.


##### ACTUAL RESULTS
fismb is still linked with fisma.
if self.diff_template(parsed_template_json, existing_template):
                changed = True
            return changed
        
        if template_groups is not None:
            existing_groups = [g['name'] for g in existing_template['zabbix_export']['groups']]
            if set(template_groups) != set(existing_groups):
                changed = True
        if 'templates' not in existing_template['zabbix_export']['templates'][0]:
            existing_template['zabbix_export']['templates'][0]['templates'] = []
        
        exist_child_templates = [t['name'] for t in existing_template['zabbix_export']['templates'][0]['templates']]
        if link_templates is not None:
            if set(link_templates) != set(exist_child_templates):
                changed = True
        else:
            if set([]) != set(exist_child_templates):
                changed = True
        
        if clear_templates is not None:
            for t in clear_templates:
                if t in exist_child_templates:
                    changed = True
                    break
        if template_macros is not None:
            existing_macros = existing_template['zabbix_export']['templates'][0]['macros']
            if template_macros != existing_macros:
                changed = True
        return changed
    def update_template(self, template_ids, group_ids, link_template_ids, clear_template_ids, template_macros):