Be mindful that it's possible to run Synapse multiple times in the same
Python process. So we only need to do some part of the logging setup
once.
- We only need to setup the global log record factory and context filter
once
- We only need to redirect Twisted logging once
### Background
As part of Element's plan to support a light form of vhosting (virtual
host) (multiple instances of Synapse in the same Python process), we're
currently diving into the details and implications of running multiple
instances of Synapse in the same Python process.
"Per-tenant logging" tracked internally by
https://github.com/element-hq/synapse-small-hosts/issues/48
2c4057bf93