Camera: Fix null pointer exception in CameraServiceProxyWrapper

Indexing into the mSessionStatsMap would insert a nullptr.
Check the count for a certain key instead.

In addition, call logStreamConfigured only when the reconfiguration
succeeds.

Test: Vendor test, Camera CTS
Bug: 287120330
Change-Id: I17d715865c9a58d3b79ab0a511a0f4968f0aa3f8