[BT] MQTT corruption fix (#2183)

Storing a copy of the ID instead of a pointer to a local variable to avoid MQTT publishing id topic and id property corruption.

partitions/alltest_large.csv

@@ -0,0 +1,4 @@
+# Name,   Type, SubType, Offset,  Size,     Flags
+nvs,      data, nvs,     0x9000,  0x5000,
+app0,     app,  ota_0,   0x10000, 0x200000,
+spiffs,   data, spiffs,  0x310000,0x4F000,