BluetoothMetrics: Remove MetricIdAllocator reference from HalCrashReason

Calling MetricIdAllocator may break its singleton pattern when stack is
half gd and half legacy. Since we are not inputing metric id at this
point, the easiest way is to just delete the reference.

Bug: 181819141
Test: atest --host bluetooth_test_common
Tag: #stability
Change-Id: If4bf0a87a55ef4ee5460065c43577ed22d7b28eb