CLN: ASV FromDictwithTimestamp
- [x] closes #18511

Also removed unnecessary `self`s and simplified method names

```
$ asv run -q -b ^frame_ctor
[  0.00%] ·· Benchmarking conda-py3.6-Cython-matplotlib-numexpr-numpy-openpyxl-pytables-pytest-scipy-sqlalchemy-xlrd-xlsxwriter-xlwt
[ 16.67%] ··· Running frame_ctor.FromDicts.time_dict                                              6.66ms
[ 33.33%] ··· Running frame_ctor.FromDicts.time_list_of_dict                                       114ms
[ 50.00%] ··· Running frame_ctor.FromDicts.time_nested_dict                                       94.1ms
[ 66.67%] ··· Running frame_ctor.FromDicts.time_nested_dict_int64                                  240ms
[ 83.33%] ··· Running frame_ctor.FromDictwithTimestamp.time_dict_with_timestamp_offsets       76.5ms;...
[100.00%] ··· Running frame_ctor.FromSeries.time_mi_series                                         328μs
```