Two tiny cleanups to convert-uast

[mppf]

This PR makes two tiny changes to convert-uast.cpp:

1. It removes an unused function that is local to this file.
2. It switches from using a query to decide if scope resolution should be attempted to checking the current modTag. (Note: we are currently using MOD_STANDARD for package modules, and as a result, only MOD_USER code is not in a bundled module. See also this code that sets modTag

   chapel/compiler/passes/parseAndConvert.cpp

   Lines 299 to 309 in 08f4df2

   	ModTag modTag = MOD_USER;
   	if (chpl::parsing::filePathIsInInternalModule(gContext, path)) {
   	modTag = MOD_INTERNAL;
   	} else if (chpl::parsing::filePathIsInStandardModule(gContext, path)) {
   	modTag = MOD_STANDARD;
   	} else if (chpl::parsing::filePathIsInBundledModule(gContext, path)) {
   	// TODO: this considers code in modules/packages as MOD_STANDARD but
   	// we would like this to be MOD_USER.
   	// See also issue #24998.
   	modTag = MOD_STANDARD;
   	}

No behavior changes in this PR.

Reviewed by @arezaii - thanks!

• full comm=none testing