DOC: Fix SS06 formatting errors in Styler docstrings
Errors fixed (from the list in #29254 ):
pandas.io.formats.style.Styler.from_custom_template
pandas.io.formats.style.Styler.apply
pandas.io.formats.style.Styler.applymap
pandas.io.formats.style.Styler.set_properties
pandas.io.formats.style.Styler.clear
pandas.io.formats.style.Styler.background_gradient
pandas.io.formats.style.Styler.use
pandas.io.formats.style.Styler.where

Validated the fixes with ```python scripts/validate_docstrings.py```
Refrencing issue: #29254 