chore: luals runtime.version only set during check, to prevent lua version ambuguity at dev time (#2975)

* chore: luals runtime.version only set during check, to prevent lua version ambuguity at dev time

* inject lua 5.1 check failure

* Revert "inject lua 5.1 check failure"

This reverts commit eed966dc7b.

.luarc.json

@@ -1,6 +1,6 @@
 {
   "$schema": "https://raw.githubusercontent.com/sumneko/vscode-lua/master/setting/schema.json",
-  "runtime.version": "Lua 5.1",
+  "runtime.version.luals-check-only": "Lua 5.1",
   "workspace": {
     "library": [
       "$VIMRUNTIME/lua/vim",