[FIX] web_editor: remove light/dark computation based on main color

Commit [1] made the "light" and "dark" colors of bootstrap be very
light and dark variations of the "main" color ("alpha" at the time, now
"o-color-1", which is used as bootstrap "primary" color). It was already
not a very good idea, although slightly better than nothing (at the time
navbar and footer colors could not be changed at all, so without this,
they would use a gray with a blueish hue not related to the main color).

Since then, 2.5 years later, [2] and [3] were made which gave some
control over bootstrap default grays via two widgets controlling the
new "gray-hue" and "gray-extra-saturation" params. At that time, the
light and dark overrides made at [1] should have been removed as "light"
and "dark" normally default to two bootstrap grays, which we would have
had control over since [2] and [3]. This was however, not a big problem
since "light" and "dark" were not used by the website templates (well it
was by some but not a lot) and the overrides to gray colors related to
the main color was not "stupid", just less nice as less control over it.

However, since the many improvements made with [4] more than 1 year
later, the "light" color started to be used to achieve more detailed
designed for the eCommerce. And it is planned to use it in further
design elements later on. The fact that those "light" elements are not
following the "grays" configuration made by the user is thus starting to
be a problem.

This commit fixes the issue in master (>= 16.1): "light" and "dark"
colors will now follow the configured grays. In the future, we might
even improve the control over those two particular grays or maybe
improve their default value according to the theme color palette.
It was judged that stable versions can stay as they are right now. As
explained, it is not critical and you can still force your own CSS rules
if you are really unhappy with the "hardcoded" grays (related to the
main color) at some places.

[1]: https://github.com/odoo/odoo/commit/22c4311e283af95eafe1ba85ee1234bb8102110e
[2]: https://github.com/odoo/odoo/commit/35d27a6c1d3dab621de7f059565d7619ae004412
[3]: https://github.com/odoo/odoo/commit/e08184103c42eaf7f6bfb70655cb90b51e79913a
[4]: https://github.com/odoo/odoo/pull/98558

Related to task-3097005

closes odoo/odoo#108825

Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/web_editor/static/src/scss/secondary_variables.scss

@@ -34,12 +34,6 @@ $o-theme-color-palette: map-merge((
     // colors by default, so that theme colors affect the default Odoo layouts
     'primary': $-main-color,
     'secondary': map-get($o-color-palette, 'o-color-2'),
-
-    // BS light and dark colors are not used for any BS component, just
-    // for color utilities. By default, we set them to a very light and
-    // very dark version of a desaturate version of the main color
-    'light': lighten(desaturate($-main-color, 80%), min(70%, max(0%, 97% - $-main-color-lightness))), // Does not increase over 97% lightness
-    'dark': darken(desaturate($-main-color, 80%), min(70%, max(0%, $-main-color-lightness - 10%))), // Does not lower under 10% lightness
 ), $o-theme-color-palette);
 $o-theme-color-palette: map-merge($o-base-theme-color-palette, $o-theme-color-palette);