Fixing threading around mConnections in Scheduler

The following happens when we create connection
1. initScheduler()
2. getFactory().createScheduler()
3. mTouchTimer.emplace
4. mScheduler->createConnection
Which means that timer created in step 3 expires exactly
while we are in step 4, so then the EventThread is half baked
in rare cases and we crash.

Also, do not continue to calling functions if the
optional fields do not have a value.

Test: libsurfaceflinger_unittest --gtest_filter=SchedulerTest.testDispatchCachedReportedConfig
Bug: 160926398
Change-Id: Ib2617b914145bc4180cc7ca27203c59dbd625c94