PERF: improves merge performance when key space exceeds i8 bounds

    -------------------------------------------------------------------------------
    Test name                                    | head[ms] | base[ms] |  ratio   |
    -------------------------------------------------------------------------------
    i8merge                                      | 1510.8590 | 13001.0207 |   0.1162 |
    merge_2intkey_nosort                         |  20.9847 |  27.0010 |   0.7772 |
    join_dataframe_index_single_key_small        |  16.4944 |  19.0903 |   0.8640 |
    join_dataframe_integer_2key                  |   7.3093 |   8.0273 |   0.9106 |
    merge_2intkey_sort                           |  60.6734 |  61.8456 |   0.9810 |
    left_outer_join_index                        | 3165.2357 | 3214.8040 |   0.9846 |
    join_dataframe_index_multi                   |  36.0967 |  36.5300 |   0.9881 |
    join_dataframe_index_single_key_bigger_sort  |  24.7893 |  25.0640 |   0.9890 |
    join_non_unique_equal                        |   0.9350 |   0.9403 |   0.9943 |
    join_dataframe_index_single_key_bigger       |  24.8820 |  24.9500 |   0.9973 |
    strings_join_split                           |  57.1507 |  56.9630 |   1.0033 |
    join_dataframe_integer_key                   |   2.9247 |   2.8093 |   1.0411 |
    -------------------------------------------------------------------------------
    Test name                                    | head[ms] | base[ms] |  ratio   |
    -------------------------------------------------------------------------------

    Ratio < 1.0 means the target commit is faster then the baseline.
    Seed used: 1234

    Target [f2d9e17] : improves merge performance when key space exceeds i8 bounds
    Base   [def58c9] : Merge pull request #9128 from hsperr/expanduser

    ENH: Expanduser in to_file methods GH9066