Don't clear throttling when network disconnects

Before the change, the throttle entries are cleared without notifying onThrottleStatusChanged via callback. Because the decision of unthrotting should only be made by modem, the fix keeps the throttle status even when network disconnects.

Also removed isAnySetupRetryScheduled(). The method in fact only checks for modem demanded retry, which is already covered by isDataProfileThrottled().

Fix: 254480678
Test: placed voice call + internet browsing
Change-Id: Id52f036fb006286411dfc53690f6b5c36e635649