Incorrect ISARIC hosttim conversion

[rebkwok]

The hosttim field on the ISARIC table is converted to a date

cohort-extractor/cohortextractor/process_covariate_definitions.py

Line 223 in 7d869e8

"hosttim": "date",

cohort-extractor/cohortextractor/tpp_backend.py

Line 3355 in 7d869e8

cast = f"CONVERT(DATE, {returning}, 103)"

However, it's actually a time (string), not a date. Converting it to date doesn't error, but it produces "1900-01-01" for all values.

Example query on db:

SELECT TOP 3 
    hosttim,
    CONVERT(DATE, hosttim, 103) as date,
    CONVERT(TIME, hostim) as time
FROM ISARIC_Patient_Data_TopLine;

hosttim	date	time
12:39:00	1900-01-01	12:39:00.0000000
11:17:00	1900-01-01	11:17:00.0000000
19:10:00	1900-01-01	19:10:00.0000000