Add additional instance info to log

When an instance can't be found, we now log the available instances.
This can help debugging when the instance name is misspelled or the
manifest fragment file wasn't included.

Test: launch_cvd && and logcat | grep "Could not find"
Test: atest servicemanager_test
Bug: 302147119
Change-Id: Iad85903d82bbd45c012b007ba1fcf059c5cd5c4a