[FIX] web_editor: Do not remove block

Do not remove block in _removeNextEmptyUnbreakable.

Before this commit, when you tried to remove insert a character in
a td, with an empty td after the first one. The function
_removeNextEmptyUnbreakable removed the empty td. It was for
example breaking snippet in the website and mass_mailing.

closes odoo/odoo#32096

Signed-off-by: Adrien Dieudonné (adr) <adr@odoo.com>

addons/web_editor/static/src/js/wysiwyg/plugin/keyboard.js

@@ -827,7 +827,7 @@ var KeyboardPlugin = AbstractPlugin.extend({
         }
     },
     /**
-     * Remove the first unbreakable ancestor's next sibling if empty.
+     * Remove the first unbreakable ancestor's next sibling if not a block and empty.
      *
      * @private
      * @param {Node} node
@@ -843,7 +843,7 @@ var KeyboardPlugin = AbstractPlugin.extend({
         var isNextContainsOnlyInvisibleText = nextUnbreakable && _.all($(nextUnbreakable).contents(), function (n) {
             return dom.isText(n) && !self.context.invoke('HelperPlugin.isVisibleText', n);
         });
-        if (isNextEmpty || isNextContainsOnlyInvisibleText) {
+        if (!dom.isBlock(nextUnbreakable) && (isNextEmpty || isNextContainsOnlyInvisibleText)) {
             $(nextUnbreakable).remove();
         }
     },