[clang][NFC] Move matcher ignoringElidableConstructorCall's tests to appropriate file.

Summary:
`ignoringElidableConstructorCall` is a traversal matcher, but its tests are
grouped with narrowing-matcher tests. This revision moves them to the correct
file.

Reviewers: gribozavr

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D65963

llvm-svn: 368326