tests: Enable system tests on Python 3.14 and fix failing generator tests

[bkeryan]

• This contribution adheres to CONTRIBUTING.md.

What does this Pull Request accomplish?

Enable system tests on Python 3.14

Update generator to sort annotation keys. Constructing a ConfigurationParameter message was implicitly sorting the annotation keys on Python 3.13 and earlier, but it started preserving order in Python 3.14, causing failures like this:

                12: ParameterMetadata(
                    display_name="Enum Array In",
                    type=Field.Kind.ValueType(14),
                    repeated=True,
                    default_value=[1, 2],
                    annotations={
  +                     "ni/enum.values": '{"NONE": 0, "RED": 1, "GREEN": 2, "BLUE": 3}',
                        "ni/type_specialization": "enum",
  -                     "ni/enum.values": '{"NONE": 0, "RED": 1, "GREEN": 2, "BLUE": 3}',
                    },
                    message_type="",
                    field_name="Enum_Array_In",
                    enum_type=EnumInEnum,
                ),

More info here: https://github.com/ni/measurement-plugin-python/pull/1258/files#r2467157116

Why should this Pull Request be merged?

Fix tests

What testing has been done?

Ran generator tests locally

[github-actions]

Test Results

    60 files  +    4      60 suites  +4   1h 22m 26s ⏱️ + 5m 52s
   689 tests ±    0     689 ✅ ±    0      0 💤 ±0  0 ❌ ±0 
24 030 runs  +1 350  22 764 ✅ +1 348  1 266 💤 +2  0 ❌ ±0 

Results for commit 41c3b40. ± Comparison against base commit 8be7fa6.