Remove llvm.src hack now that llvm-project is in use

The master appears to have restarted, and the annotated bots seem to be
using stale checkouts. They didn't see the Dexter change.

zorg/buildbot/builders/annotated/annotated_builder.py

@@ -298,11 +298,6 @@ def run_steps(
         cwd = os.getcwd()
         source_dir = pjoin(cwd, 'llvm-project')
         build_dir = pjoin(cwd, 'build')
-        # If llvm-project doesn't exist, use llvm.src, the old location.
-        # TODO: Remove this after a master restart.
-        if not os.path.exists(source_dir):
-            source_dir = pjoin(cwd, '../llvm.src')
-            build_dir = cwd
         cmake_args = ['-GNinja', '-DLLVM_ENABLE_PROJECTS=' + ';'.join(projects)]
 
         try: