Remove ImplicitStringConcatShapes template and generator from tests

This is a cleanup as a part of enabling TestNG tests on host. Vogar
interprets this file as a test when in reality it is a test generator,
so remove template and generator class from tests completely.

Bug: 208639267
Test: art/tools/run-libcore-tests.sh --mode host \
      test.java.lang.String.concat
Change-Id: I9ef434efbb76b89ac2bea1136fb264070eb5891a
2 files changed