Set `"eslint.useFlatConfig": true` for vscode-eslint extension

and remove now invalid "resolvePluginsRelativeTo" option.

.vscode/settings.json

@@ -6,9 +6,7 @@
   "editor.insertSpaces": true,
   "editor.tabSize": 2,
   "eslint.workingDirectories": [{ "pattern": "./sdk/*/*/" }],
-  "eslint.options": {
-    "resolvePluginsRelativeTo": "../../../common/tools/eslint-plugin-azure-sdk-helper"
-  },
+  "eslint.useFlatConfig": true,
   "files.exclude": {
     "**/.git": true,
     "**/.svn": true,

dataplane.code-workspace

@@ -314,9 +314,7 @@
     "files.exclude": {
       "**/node_modules": true
     },
-    "eslint.options": {
-      "resolvePluginsRelativeTo": "../../../common/tools/eslint-plugin-azure-sdk-helper"
-    }
+    "eslint.useFlatConfig": true
   },
   "extensions": {
     "recommendations": [