[Bug] Fix issue with Repeat Key-Combo test (#21005)

tests/repeat_key/repeat_key_combo/test.mk

@@ -16,3 +16,4 @@
 REPEAT_KEY_ENABLE = yes
 
 COMBO_ENABLE = yes
+INTROSPECTION_KEYMAP_C = test_combos.c

tests/repeat_key/repeat_key_combo/test_combos.c

@@ -0,0 +1,8 @@
+// Copyright 2023 Stefan Kerkmann (@KarlK90)
+// Copyright 2023 @filterpaper
+// Copyright 2023 Nick Brassel (@tzarc)
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include "quantum.h"
+
+const uint16_t xy_combo[] PROGMEM = {KC_X, KC_Y, COMBO_END};
+combo_t        key_combos[]       = {COMBO(xy_combo, KC_Q)};

tests/repeat_key/repeat_key_combo/test_repeat_key_combo.cpp

@@ -24,13 +24,6 @@ using ::testing::InSequence;
 
 namespace {
 
-extern "C" {
-// Define a combo: KC_X + KC_Y = KC_Q.
-const uint16_t xy_combo[] PROGMEM = {KC_X, KC_Y, COMBO_END};
-combo_t        key_combos[]       = {COMBO(xy_combo, KC_Q)};
-uint16_t       COMBO_LEN          = sizeof(key_combos) / sizeof(*key_combos);
-} // extern "C"
-
 class RepeatKey : public TestFixture {};
 
 // Tests repeating a combo, KC_X + KC_Y = KC_Q, by typing