Don't show alembic info logs at the start of every cli command (#21758)
Don't show alembic info logs at the start of every cli command (#21758)

We recently merged a change where we check if DB migrations
are pending before running the main command, but this had the
side-effect of showing these two log lines from alembic:

```
[2022-02-22 18:06:01,995] {{migration.py:201}} INFO - Context impl PostgresqlImpl.
[2022-02-22 18:06:01,995] {{migration.py:204}} INFO - Will assume transactional DDL.
```

Which is a) not useful information to a user, and b) "pollutes" the
output if a command was producing JSON or some other structured format
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