[CH] JSON input format can not parse while key's case not match

### Backend

CH (ClickHouse)

### Bug description

when define a table like `(a string, b string)` and use json format, when the input is {"a":"A1", "B":"B1"}, then the field `b` can not be parsed, as the key not matched.

### Spark version

Spark-3.3.x

### Spark configurations

_No response_

### System information

_No response_

### Relevant logs

_No response_

Start by reproducing the reported Spark 3.3.x ClickHouse JSON-input case with a table containing `a` and `b` and input keys `a` and `B`, then trace the ClickHouse JSON parsing entry point. Done means the case-mismatched `B` key populates column `b` consistently, with a regression test covering the behavior.

Written by the indexing model from the issue text.