Clean up and migrate Azure tests. (#28103)

* Remove placeholder Azure test.
* Migrate Azure tests to ansible-test.
* Initial cleanup on remaining legacy Azure tests.

test/integration/targets/azure_rm_subnet/tasks/main.yml

@@ -0,0 +1,95 @@
+- name: Create virtual network
+  azure_rm_virtualnetwork:
+    name: My_Virtual_Network
+    address_prefixes_cidr:
+      - 10.1.0.0/16
+      - 172.100.0.0/16
+    dns_servers:
+      - 127.0.0.1
+      - 127.0.0.3
+    tags:
+      testing: testing
+      delete: on-exit
+    resource_group: "{{ resource_group }}"
+
+- name: Remove subnet
+  azure_rm_subnet:
+    state: absent
+    name: foobar
+    virtual_network_name: My_Virtual_Network
+    resource_group: "{{ resource_group }}"
+
+- name: Catch invalid cidr
+  azure_rm_subnet:
+    name: foobar
+    virtual_network_name: My_Virtual_Network
+    resource_group: "{{ resource_group }}"
+    address_prefix_cidr: "10.1.0/24"
+  register: output
+  ignore_errors: yes
+
+- assert:
+    that: output.failed
+
+- name: Add the subnet back
+  azure_rm_subnet:
+    name: foobar
+    virtual_network_name: My_Virtual_Network
+    resource_group: "{{ resource_group }}"
+    address_prefix_cidr: "10.1.0.0/24"
+  register: output
+
+- assert:
+    that: output.changed
+
+- name: Create network security group
+  azure_rm_securitygroup:
+    name: secgroupfoo
+    resource_group: "{{ resource_group }}"
+    tags:
+      testing: testing
+
+- name: Update the subnet
+  azure_rm_subnet:
+    name: foobar
+    virtual_network_name: My_Virtual_Network
+    resource_group: "{{ resource_group }}"
+    address_prefix_cidr: "10.1.0.0/16"
+    security_group: secgroupfoo
+    tags:
+       testing: testing
+       delete: on-fini
+
+- name: Should be idempotent
+  azure_rm_subnet:
+    name: foobar
+    virtual_network_name: My_Virtual_Network
+    resource_group: "{{ resource_group }}"
+    address_prefix_cidr: "10.1.0.0/16"
+    security_group: secgroupfoo
+    tags:
+       testing: testing
+       delete: on-fini
+  register: output
+
+- assert:
+    that: not output.changed
+
+- name: Remove subnet
+  azure_rm_subnet:
+    state: absent
+    name: foobar
+    virtual_network_name: My_Virtual_Network
+    resource_group: "{{ resource_group }}"
+
+- name: Remove security group
+  azure_rm_securitygroup:
+    resource_group: "{{ resource_group }}"
+    name: secgroupfoo
+    state: absent
+
+- name: Remove virtual network
+  azure_rm_virtualnetwork:
+    name: My_Virtual_Network
+    resource_group: "{{ resource_group }}"
+    state: absent