BAU: dont override user workspace colour preferences

Remove the colour customisations specified at the repository configuration level.

Developers can still specify their own customisations for the workspaces.

The current version of vscode has very little contrast with the chosen colour scheme
which makes it hard to use.

This also removes an override for formatting on saving which can also now be
chosen by the developer based on their setup -- formatting issues should be
caught in pre-commit checks both locally and during the CI process.

.vscode/settings.json

@@ -1,10 +1,4 @@
 {
-  "workbench.colorCustomizations": {
-    "activityBar.background": "#10a84a",
-    "titleBar.activeBackground": "#10a84a",
-    "titleBar.activeForeground": "#ffffff"
-  },
-  "editor.formatOnSave": false,
   "python.testing.pytestArgs": [
     "tests"
   ],