[experiments] Fix bug in codegen for debug experiments (#33282)

Somehow this was missed earlier because none of the experiments were
enabled in debug builds.

tools/codegen/core/experiments_compiler.py

@@ -326,7 +326,7 @@ class ExperimentsCompiler(object):
                     "const char* const additional_constraints_%s = %s;" %
                     (exp.name, ToCStr(json.dumps(exp.additional_constraints))),
                     file=C)
-                have_defaults.add(exp.default)
+                have_defaults.add(self._defaults[exp.default])
             if 'kDefaultForDebugOnly' in have_defaults:
                 print("#ifdef NDEBUG", file=C)
                 if 'kDefaultForDebugOnly' in have_defaults:

tools/codegen/core/gen_experiments.py

@@ -39,7 +39,7 @@ FINAL_RETURN = {
     'broken': 'return false;',
     False: 'return false;',
     True: 'return true;',
-    'debug': '#ifdef NDEBUG\nreturn false;\n#else\nreturn true;\n#endif',
+    'debug': '\n#ifdef NDEBUG\nreturn false;\n#else\nreturn true;\n#endif\n',
 }
 
 FINAL_DEFINE = {