fix(k17): remove dead custom keycode stubs from tap-chord dance

CK_CTRL_K_C and CK_CTRL_K_D were leftover from an earlier failed
attempt using ACTION_TAP_DANCE_DOUBLE with custom keycodes. Now that
TD_CHORDS uses ACTION_TAP_DANCE_FN with SEND_STRING, they are unused.

keyboards/keychron/k17_max/ansi_encoder/rgb/keymaps/via/keymap.c

@@ -24,10 +24,13 @@ enum {
     TD_CHORDS,
 };
 
-enum custom_keycodes {
-    CK_CTRL_K_C = NEW_SAFE_RANGE,
-    CK_CTRL_K_D,
-};
+void dance_chords_finished(tap_dance_state_t *state, void *user_data) {
+    if (state->count == 1) {
+        SEND_STRING(SS_LCTL("kc"));
+    } else {
+        SEND_STRING(SS_LCTL("kd"));
+    }
+}
 
 enum layers {
     MAC_BASE,
@@ -85,18 +88,6 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
     if (!process_record_keychron_common(keycode, record)) {
         return false;
     }
-    switch (keycode) {
-        case CK_CTRL_K_C:
-            if (record->event.pressed) {
-                SEND_STRING(SS_LCTL("kc"));
-            }
-            return false;
-        case CK_CTRL_K_D:
-            if (record->event.pressed) {
-                SEND_STRING(SS_LCTL("kd"));
-            }
-            return false;
-    }
     return true;
 }
 
@@ -104,5 +95,5 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
 tap_dance_action_t tap_dance_actions[] = {
     // Tap once for Home, twice for End
     [TD_HOME_END] = ACTION_TAP_DANCE_DOUBLE(KC_HOME, KC_END),
-    [TD_CHORDS]   = ACTION_TAP_DANCE_DOUBLE(CK_CTRL_K_C, CK_CTRL_K_D),
+    [TD_CHORDS]   = ACTION_TAP_DANCE_FN(dance_chords_finished),
 };