Revert "Add setting to show/hide title bar (#37428)" (#38756)

Closes https://github.com/zed-industries/zed/issues/38547

Release Notes:

- Reverted the ability to show/hide the titlebar. This caused rendering
bugs on
macOS, and we're preparing for the redesign which requires the toolbar
being present.

---------

Co-authored-by: Kirill Bulatov <kirill@zed.dev>

docs/src/configuring-zed.md

@@ -4140,7 +4140,6 @@ Run the {#action theme_selector::Toggle} action in the command palette to see a
 
 ```json
 "title_bar": {
-  "show": "always",
   "show_branch_icon": false,
   "show_branch_name": true,
   "show_project_items": true,

docs/src/visual-customization.md

@@ -108,7 +108,6 @@ To disable this behavior use:
 ```json
   // Control which items are shown/hidden in the title bar
   "title_bar": {
-    "show": "always",               // When to show: always | never | hide_in_full_screen
     "show_branch_icon": false,      // Show/hide branch icon beside branch switcher
     "show_branch_name": true,       // Show/hide branch name
     "show_project_items": true,     // Show/hide project host and name