P4P tests are a bit slow

[GDYendell]

========================================================================================================================== slowest 10 durations ===========================================================================================================================
3.01s call     tests/transport/epics/pva/test_p4p.py::test_command_method_put_twice
2.88s call     tests/transport/epics/pva/test_p4p.py::test_scan_method
1.26s setup    tests/test_docs_snippets.py::test_snippet[docs/snippets/static01.py]
0.73s setup    tests/transport/epics/pva/test_p4p.py::test_ioc
0.73s setup    tests/transport/epics/ca/test_softioc_system.py::test_ioc
0.62s call     tests/transport/epics/pva/test_p4p.py::test_command_method
0.61s call     tests/transport/epics/pva/test_p4p.py::test_more_exotic_dataypes
0.50s call     tests/transport/epics/pva/test_p4p.py::test_block_flag_waits_for_callback_completion
0.43s call     tests/transport/epics/ca/test_softioc_system.py::test_ioc
0.21s call     tests/transport/epics/pva/test_p4p.py::test_pvi_grouping

Investigate and try to get each test down to ~1 second