Temporarily disable 2.15 sanity tests

[mariolenz]

Temporarily disable 2.15 sanity tests. At the moment, they fail with:

ERROR: Found 2 validate-modules issue(s) which need to be resolved:
ERROR: plugins/modules/vmware_portgroup.py:0:0: incompatible-choices: Argument 'load_balancing' in argument_spec found in teaming defines choices as (None) but this is incompatible with argument type 'str'
ERROR: plugins/modules/vmware_vswitch.py:0:0: incompatible-choices: Argument 'load_balancing' in argument_spec found in teaming defines choices as (None) but this is incompatible with argument type 'str'
See documentation for help: https://docs.ansible.com/ansible-core/devel/dev_guide/testing/sanity/validate-modules.html
Running sanity test "yamllint"
Run command with data: /root/.ansible/test/venv/sanity.yamllint/3.11/61ebfb13/bin/python /root/ansible/test/lib/ansible_test/_util/controller/sanity/yamllint/yamllinter.py
FATAL: The 1 sanity test(s) listed below (out of 46) failed. See error output above for details.
validate-modules

#1747

[softwarefactory-project-zuul]

Build succeeded.
https://ansible.softwarefactory-project.io/zuul/buildset/8ee746d4761e4e4194d2c63208eaca6a

✔️ ansible-tox-linters SUCCESS in 8m 31s
✔️ build-ansible-collection SUCCESS in 9m 16s
✔️ ansible-galaxy-importer SUCCESS in 3m 31s

[softwarefactory-project-zuul]

Build succeeded (gate pipeline).
https://ansible.softwarefactory-project.io/zuul/buildset/c9a9e17567e040a4aaffb426aaacb2ce

✔️ ansible-tox-linters SUCCESS in 9m 18s
✔️ build-ansible-collection SUCCESS in 7m 25s
✔️ ansible-galaxy-importer SUCCESS in 3m 58s

[softwarefactory-project-zuul]

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