[test] Clean up Driver/baremetal.cpp

* Remove -no-canonical-prefixes. See 9806799
* Test a.out and %t.out in few tests and remove excess `-o %t.o`
* Avoid wrapping lines too aggresstively
* Replace `"{{[^"]*}}ld{{(\.(lld|bfd|gold))?}}{{(\.exe)?}}"` with `ld{{(.exe)?}}"`. The new pattern supports more CLANG_DEFAULT_LINKER.

Author: MaskRay