##### 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.
template_json_a = self.filter_template(template_json_a)
        template_json_b = self.filter_template(template_json_b)
        if self.ordered_json(template_json_a) == self.ordered_json(template_json_b):
            return False
        return True
    def filter_template(self, template_json):
        
        keep_keys = set(['graphs', 'templates', 'triggers', 'value_maps'])
        unwanted_keys = set(template_json['zabbix_export']) - keep_keys
        for unwanted_key in unwanted_keys:
            del template_json['zabbix_export'][unwanted_key]
        
        desc_not_supported = False
        if LooseVersion(self._zapi.api_version()).version[:2] < LooseVersion('2.4').version:
            desc_not_supported = True
        
        for template in template_json['zabbix_export']['templates']:
            for key in list(template.keys()):
                if not template[key] or (key == 'description' and desc_not_supported):
                    template.pop(key)
        return template_json
    def filter_xml_template(self, template_xml):