BUG: read_json(line=True) returns Index instead of RangeIndex in 2.2 #57429
Description
In [2]: import pandas as pd; from io import StringIO
In [3]: data = """\
...: {"a": 1, "b": 2}
...: {"a": 3, "b": 4}"""
In [4]: pd.read_json(StringIO(data), lines=True).index
Out[4]: Index([0, 1], dtype='int64'). # main
Out[3]: RangeIndex(start=0, stop=2, step=1). # 2.1