fix: commit boost cb-config

[koikonom]

Commit boost crashes on startup with the following message:

Error:
   0: could not deserialize toml from string
   1: TOML parse error at line 12, column 2
   1:    |
   1: 12 | [logs.stdout]
   1:    |  ^^^^
   1: missing field `file`
   1:

The workaround is to explicitly disable file logging, since we do
not need it for this use case anyway.

Please note that this is only needed for commit-boost 0.8.0. A fix
for this issue has been merged in v0.8.1-rc.2.