Revert "Fix backwards compatability with `Lua.workspace.checkThirdParty`"

This reverts commit 13a24eef.

script/library.lua

@@ -610,13 +610,9 @@ local function check3rd(uri)
     end
     local checkThirdParty = config.get(uri, 'Lua.workspace.checkThirdParty')
     -- Backwards compatability: `checkThirdParty` used to be a boolean.
-    -- Note: `checkThirdParty` is defined as a string, so if a boolean is
-    -- supplied, it's converted to a string by the `config.config` module.
-    -- Hence we check for the strings `'true'` and `'false`' here, rather than
-    -- the boolean literals.
-    if checkThirdParty == 'Disable' or checkThirdParty == 'false' then
+    if not checkThirdParty or checkThirdParty == 'Disable' then
         return
-    elseif checkThirdParty == 'true' then
+    elseif checkThirdParty == true then
         checkThirdParty = 'Ask'
     end
     local scp = scope.getScope(uri)