DOC: Add linspace range behavior to the timeseries/timedeltas/interval docs
Follow-up to #21009

`timeseries.rst`:
- Added documentation for linspace behavior of `date_range`

`timedeltas.rst`:
- Cleaned up `timedelta_range` documentation for the standard behavior
- Added documentation for linspace behavior of `timedelta_range`

`advanced.rst`:
- Added documentation for the standard behavior of `interval_range`
- Added documentation for linspace behavior of `interval_range`