T5803: Migrate vscode settings to new value and clean up .gitattributes

Update VSCode settings for "editor.wordBasedSuggestions". It has
changed from boolean to enum. The value "off" is the same as previous
value of `false`.

Also remove stray duplicate entries in .gitattributes.

.gitattributes

@@ -73,8 +73,3 @@
 .gitkeep              export-ignore
 *.pyc          binary export-ignore
 *.pyo          binary export-ignore
-
-#
-# Enable syntax highlighting for VSCode settings
-#
-.vscode/settings.json linguist-language=jsonc

.vscode/settings.json

@@ -10,7 +10,7 @@
         "*.xml.in": "xml",
     },
     "[jinja]": {
-        "editor.wordBasedSuggestions": false
+        "editor.wordBasedSuggestions": "off"
     },
     // https://code.visualstudio.com/docs/python/settings-reference
     "python.analysis.extraPaths": [