Summary:
when ON_ERROR_STOP is not set, dumps can restore even if there's a
syntax error. That's not really a sensible thing to do.

Also add --no-psqlrc because my psqlrc has stuff in it that makes psql noisy in
batch mode (\timing).

Test Plan:
Run the swh-vault tests, which are the only ones to use this fixture
in this mode

Reviewers: #reviewers!

Differential Revision: https://forge.softwareheritage.org/D307

Related T1036

Related T1036

change cherry picked from python module template
commit 71b117ba0cf9f1251b1cac26d0994df03a4c787d

This will help create new logging handlers.

Related T700

The previous behavior would try catching the builtin ConnectionError, that
requests never raises.

Related T646

Related T646

Related T646

What we want to check here is that the value is not defined, not that it
is falsy.

Also use the opportunity to truncate long arguments lists as they are
unlikely to ever be useful...

This allows reading in yaml files in priority_read

yaml config files (extension .yml) get parsed as the original ini files
would be.

To permit to use multiple dbs in a test context.
Reuse same principle as DbTestFixture

cf. swh.storage.archiver's tests