[FIX] web: remove min-height of form sheet within a modal

We added min-height for `o_form_sheet` in form view with a commit[1] restoring
the views design (after views refactoring).

However, the min-height isn't very useful when form view is opened witin a
modal (FormViewDialog). Especially, when the form view is having only few
fields, the `o_form_sheet` container occupies unnecessary height and looks
a bit ugly.

This commit fixes the issues by setting the min-height to `0` for
`o_form_sheet` container in such cases.

[1] - https://github.com/odoo/odoo/commit/250e716c3a12#diff-01e46b3171a7282967199e5d45fca0e6R15



TaskID: 2150471
PR #41619

closes odoo/odoo#43336

X-original-commit: 8b030ede
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/web/static/src/scss/form_view_extra.scss

@@ -185,6 +185,9 @@
         .o_form_sheet_bg, .o_form_sheet {
             border: none;
         }
+        .o_form_sheet_bg > .o_form_sheet {
+            min-height: 0;
+        }
     }
 }