fix(http): HTTP version, data and start-line messages lack the HTTP: prefix #2298

Describe the bug
Most HTTP messages read HTTP: invalid format or HTTP/2: [Type N] …, but these break the <prefix>: <lowercase description>: … {value!r} form (#2232, #2257):

• http.HTTP.read / make: invalid HTTP version: 3. _make_data: invalid HTTP data: Raw. _guess_version: unknown HTTP version.
• httpv1.HTTP._make_start_line: HTTP request must have URI. and HTTP packet must be either request or response. These are capitalised, end with a full stop and don't name the offending argument.
• httpv2.HTTP._make_http_settings: HTTP/2 : [Type 4] invalid settings. It has a space before the colon, and the rejected value isn't shown.

Reproduction (main 9d504ead5)

>>> HTTP.make(HTTP.__new__(HTTP), version=3)
ProtocolError: invalid HTTP version: 3
>>> H2.__new__(H2)._make_http_settings(settings=42)
ProtocolError: HTTP/2 : [Type 4] invalid settings

Expected behavior
For example HTTP: invalid version: 3, HTTP: unknown version, HTTP: invalid start line: a request needs a URI, HTTP/2: [Type 4] invalid settings: 42. Pins to update: test_http_unit asserts str(ctx.exception) == 'unknown HTTP version' and lists it in a table of expected messages, and test_http_guess_http2_1141_unit / test_http_from_data_1154_unit match unknown HTTP version / invalid HTTP data by regex.

System information
Linux, CPython 3.14.9, checkout main 9d504ead5.