[clang] [clang][ASTImporter] Remove 'hasReturnTypeDeclaredInside' (PR #169504)

[Balázs Kéri via cfe-commits]

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balazske wrote:

In my opinion this test is not "fundamentally" different, "constraintsatisfaction.cpp" and "cxxdefaultinitexpr.cpp" are somewhat similar. These tests were added to check crash fixes which is true for the new test too (probably the intent of the code change was different). If a "regression" folder is created, more of the existing tests that do not check for CTU feature correctness (but not sure which ones exactly) should be put into it.

https://github.com/llvm/llvm-project/pull/169504