[clang][deps] Fix failing modules.cpp test

Commit d8bab69e updated the ClangScanDeps/modules.cpp test. The new `{{.*}}` regex is supposed to only match `modules_cdb_input.o`, `a.o` or `b.o`. However, due to non-determinism, this can sometimes also match `modules_cdb_input2.o`, causing match failure on the next line. This commit changes the regex to only match one of the three valid cases.

Buildbot failure: https://lab.llvm.org/buildbot/#/builders/109/builds/16675