BUG: read_json(line=True) returns `Index` instead of `RangeIndex` in 2.2

[mroeschke]

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

[VISWESWARAN1998]

In Line 1163: Index object is explicitly created (which I commented out and used the existing index of newly generated series)

After changes:

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

print(pd.read_json(StringIO(data), lines=True).index)

gives me expected results:

[1/1] Generating write_version_file with a custom command
IntervalIndex([ (1.0, 2.0),  (2.0, 3.0),  (3.0, 4.0),  (4.0, 5.0),  (5.0, 6.0),
                (6.0, 7.0),  (7.0, 8.0),  (8.0, 9.0), (9.0, 10.0)],
              dtype='interval[float32, neither]')
RangeIndex(start=0, stop=2, step=1)