BUG: Fix JsonReader to handle nrows more robustly

[bilichboris]

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This PR fixes inconsistent behavior of JsonReader with lines=True, when chunksize does not divide nrows or when nrows=0. This can be illustrated by the following two snippets:

import pandas as pd
from io import StringIO

jsonl = """{"a": 1, "b": 2}
{"a": 3, "b": 4}
{"a": 5, "b": 6}
{"a": 7, "b": 8}"""

reader = pd.read_json(StringIO(jsonl), lines=True, nrows=3, chunksize=2)
result = pd.concat(reader)

# Should be exactly 3 rows; pre-fix returns 4.
assert len(result) == 3, f"expected 3 rows, got {len(result)}"

jsonl = """{"a": 1, "b": 2}
{"a": 3, "b": 4}
"""

result = pd.read_json(StringIO(jsonl), lines=True, nrows=0)
assert len(result) == 0, f"expected 0 rows, got {len(result)}" # got 2

[rhshadrach]

Looking good!

[rhshadrach]

Do we validate that if these are not None, then nrows is nonnegative and chunksize is positive?

[rhshadrach]

I think this block can just be removed

[rhshadrach]

Can you move the note to 3.1.0 since this is not a regression.