Some general Python test improvements (#2316)

This PR originally contained a fix for sqlx which turned out not not to be necessary. But on the way, I made some general improvements:

- Under some circumstances, a "normal" test failure led to a timeout, without printing a decent error message. See e.g. https://app.circleci.com/pipelines/github/deltachat/deltachat-core-rust/8069/workflows/ba2a9949-b4ad-4ceb-a930-073bba05e2db/jobs/30965.
  (The problem was: if there is an exception in dc_account_extra_configure(), when trying to handle the exception the line account.log("===================", e, "===================") was called, which can't work as log() only expects one parameter)
- When a test fails: Call `dump_account_info()` even if there is no direct_imap
- In test_import_export_online_all(), add another 100KB file to the backup. This adds resilience against future size changes of the sql db file: The test tests the smoothness of the progress bar. And if there are there are not enough about-equally-sized files, the progress bar can't be smooth.

python/src/deltachat/account.py

@@ -89,6 +89,22 @@ class Account(object):
             d[key.lower()] = value
         return d
 
+    def dump_account_info(self, logfile):
+        def log(*args, **kwargs):
+            kwargs["file"] = logfile
+            print(*args, **kwargs)
+
+        log("=============== " + self.get_config("displayname") + " ===============")
+        cursor = 0
+        for name, val in self.get_info().items():
+            entry = "{}={}".format(name.upper(), val)
+            if cursor + len(entry) > 80:
+                log("")
+                cursor = 0
+            log(entry, end=" ")
+            cursor += len(entry) + 1
+        log("")
+
     def set_stock_translation(self, id, string):
         """ set stock translation string.