[FIX] web_editor, website: avoid updating the DOM when selecting a link

When `link_tools` was introduced at [1], `_onURLInput` did only update
the configuration form and did not touch the edited DOM. Even though its
name would be misleading for that purpose, it was therefore used without
issue as an event handler responding to the configuration form input
events and as a private method called in the `start` method of the
widget lifecycle.

At a later stage, with [2], DOM modifications were introduced in
`_onURLInput` (using the misleading `_adaptPreview` method whose
refactoring at [3] made it update the configuration form only in the
case of the "Link Dialog" but update the actual link DOM for the "Link
tools" (website / mass mailing)).

This commit fixes that behavior by touching what is strictly necessary
in stable to keep the original intend of `_onURLInput` (updating the
configuration UI) but at the same time update the DOM following
configuration form input events (as intended by [2]).
In master, all of this should be reviewed.

Here are steps which revealed the problem. Although, meanwhile, [4] and
its parents were merged which fixed other parts of this issue but
keeping the potentially problematic DOM update on selection as described
above. Notice that [4] and its parents may be reviewed further in a
future update.
- Edit Home page
- Drop a "Banner" block
- Select the "Contact Us" button
- Select "Custom" style in the link tool
- Select a fill color
- Deselect the button by clicking on the Banner's text
- Select the button again
=> Button is redrawn without its color

[1]: https://github.com/odoo/odoo/commit/740168ce8d27da3d6a7156d2d79655a898394923
[2]: https://github.com/odoo/odoo/commit/226c4c4032c26d3d8f622b29fb151fa8e78ba70a
[3]: https://github.com/odoo/odoo/commit/4a1d776243b059d423152bd026bb8bc758477224
[4]: https://github.com/odoo/odoo/commit/eb4edac560227b46efdcfe958e3b93e0b88def64



opw-3086198
task-3096806

X-original-commit: da25eadd
Part-of: odoo/odoo#108812
Co-authored-by: qsm-odoo <qsm@odoo.com>