Do not deselect in terminal on copy by default (#39814)

Release Notes:

- Flips `terminal.keep_selection_on_copy` default to `true`

docs/src/configuring-zed.md

@@ -3512,7 +3512,7 @@ List of `integer` column numbers
     "alternate_scroll": "off",
     "blinking": "terminal_controlled",
     "copy_on_select": false,
-    "keep_selection_on_copy": false,
+    "keep_selection_on_copy": true,
     "dock": "bottom",
     "default_width": 640,
     "default_height": 320,
@@ -3690,7 +3690,7 @@ List of `integer` column numbers
 
 - Description: Whether or not to keep the selection in the terminal after copying text.
 - Setting: `keep_selection_on_copy`
-- Default: `false`
+- Default: `true`
 
 **Options**
 
@@ -3701,7 +3701,7 @@ List of `integer` column numbers
 ```json
 {
   "terminal": {
-    "keep_selection_on_copy": true
+    "keep_selection_on_copy": false
   }
 }
 ```