Set Installation ID as user ID fallback for Metrics and Logs

[adinauer]

Description

We could set Installation.id as fallback in case no user ID has been set.

We can do this for both Metrics and Logs.

Also see #4995 (comment) for more details

[linear]

JAVA-276

[romtsn]

closing this since we already set distinctId (which is Installation.id under-the-hood) both to metrics and logs.