pgsql: Prevent CRLF conversion of inputs in json_parser test module

Prevent CRLF conversion of inputs in json_parser test module

Do this by opening the file in PG_BINARY_R mode. This prevents us from
getting wrong byte count from stat().

Per complaint from Andres Freund

Discussion: https://postgr.es/m/20240707052030.r77hbdkid3mwksop@awork3.anarazel.de

Backpatch to rlease 17 where this code was introduced

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/f7bd0a381de12a5c309f3c19d8c966b77e87cff3

Modified Files
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src/test/modules/test_json_parser/test_json_parser_incremental.c | 2 +-
src/test/modules/test_json_parser/test_json_parser_perf.c        | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)