Restore linux ctrl-d functionality (#15238)

- Restore `ctrl-d` functionality accidentally removed
- Remove duplicate `ctrl-d` keymap in `Editor` context (dead)

assets/keymaps/default-linux.json

@@ -40,7 +40,6 @@
       "backspace": "editor::Backspace",
       "shift-backspace": "editor::Backspace",
       "delete": "editor::Delete",
-      "ctrl-d": "editor::Delete",
       "tab": "editor::Tab",
       "shift-tab": "editor::TabPrev",
       "ctrl-k": "editor::CutToEndOfLine",
@@ -269,6 +268,7 @@
       "alt-shift-left": "editor::SelectSmallerSyntaxNode", // Shrink Selection
       "ctrl-shift-l": "editor::SelectAllMatches", // Select all occurrences of current selection
       "ctrl-f2": "editor::SelectAllMatches", // Select all occurrences of current word
+      "ctrl-d": ["editor::SelectNext", { "replace_newest": false }],
       "ctrl-shift-down": ["editor::SelectNext", { "replace_newest": false }], // Add selection to Next Find Match
       "ctrl-shift-up": ["editor::SelectPrevious", { "replace_newest": false }],
       "ctrl-k ctrl-d": ["editor::SelectNext", { "replace_newest": true }],