Remove python2 related CI

[stephenchengCloud]

The code has already been tested by python3.
Remove python2 test from the CI actions.

============================= test session starts ==============================
platform linux -- Python 3.11.9, pytest-8.3.2, pluggy-1.5.0 -- /home/runner/.cache/pre-commit/repom96bpdxe/py_env-**python3.11/bin/python**
cachedir: .pytest_cache
rootdir: /home/runner/work/xen-api/xen-api
configfile: pyproject.toml
testpaths: python3, **ocaml/xcp-rrdd, ocaml/xenopsd**

.....

ocaml/xcp-rrdd/scripts/rrdd/test_api_wait_until_next_reading.py::test_params[None-5-reading0-5] PASSED [ 87%]
ocaml/xcp-rrdd/scripts/rrdd/test_api_wait_until_next_reading.py::test_params[1-5-reading1-5] PASSED [ 88%]
ocaml/xcp-rrdd/scripts/rrdd/test_api_wait_until_next_reading.py::test_params[2.25-5-reading2-3.75] PASSED [ 89%]
ocaml/xcp-rrdd/scripts/rrdd/test_api_wait_until_next_reading.py::test_params[0.5-30-reading3-30] PASSED [ 90%]
ocaml/xcp-rrdd/scripts/rrdd/test_api_wait_until_next_reading.py::test_params[2-120-reading4-120] PASSED [ 91%]
ocaml/xcp-rrdd/scripts/rrdd/test_api_wait_until_next_reading.py::test_params[11-5-reading5-0] PASSED [ 91%]
ocaml/xcp-rrdd/scripts/rrdd/test_api_wait_until_next_reading.py::test_params[1-10-reading6-0] PASSED [ 92%]
ocaml/xcp-rrdd/scripts/rrdd/test_api_wait_until_next_reading.py::test_params[1-9-reading7-9] PASSED [ 93%]
ocaml/xcp-rrdd/scripts/rrdd/test_api_wait_until_next_reading.py::test_params[1-10-reading8-8] PASSED [ 94%]
ocaml/xcp-rrdd/scripts/rrdd/test_api_wait_until_next_reading.py::test_params[1-7-reading9-5] PASSED [ 95%]
ocaml/xcp-rrdd/scripts/rrdd/test_api_wait_until_next_reading.py::test_api_getter_functions PASSED [ 95%]
ocaml/xenopsd/scripts/test_igmp_query_injector.py::TestXSWatcher::test_unwatch PASSED [ 96%]
ocaml/xenopsd/scripts/test_igmp_query_injector.py::TestXSWatcher::test_watch PASSED [ 97%]
ocaml/xenopsd/scripts/test_igmp_query_injector.py::TestIGMPQueryInjector::test_inject_with_connection_state_check_succ PASSED [ 98%]
ocaml/xenopsd/scripts/test_igmp_query_injector.py::TestIGMPQueryInjector::test_inject_with_connection_state_check_timeout PASSED [ 99%]
ocaml/xenopsd/scripts/test_igmp_query_injector.py::TestIGMPQueryInjector::test_inject_without_connection_state_check PASSED [100%]
...
Name                                                Stmts   Miss  Cover
-----------------------------------------------------------------------
ocaml/xcp-rrdd/scripts/rrdd/rrdd.py                   171     83    51%
ocaml/xenopsd/scripts/igmp_query_injector.py          144     51    65%
ocaml/xenopsd/scripts/test_igmp_query_injector.py      73      1    99%