Fix receating APN list after other SIM is removed

The dummy SUB ID can be returned while the SUB to slot map is
rebuilding due to race condition, so that the previous SUB is
written as dummy SUB ID even its SIM is still present.

To fix it, avoid writing the previous SUB cache while SUB is not
active, after SIM is not ready, the previous SUB cache can be reset.

Bug: 111906758
Change-Id: I08ed7706a4adc8943783c53c879cc6f9af17a0bb