ensure exceptions in reply job processing don't crash the application

[redshiftzero]

Description

#820 consists of two parts:

1. Ensuring that exceptions in reply job processing cannot crash the app, and
2. Resolving races between the sync and the reply job (see comment here).

This just addresses the first part. I do not see crashers now locally, instead the reply will show up as failed.

Test Plan

1. Apply diff here from the case @creviera found:

diff --git a/securedrop_client/api_jobs/uploads.py b/securedrop_client/api_jobs/uploads.py
index 8616b71..dac78c1 100644
--- a/securedrop_client/api_jobs/uploads.py
+++ b/securedrop_client/api_jobs/uploads.py
@@ -98,7 +98,7 @@ class SendReplyJob(ApiJob):
         # TODO: Once https://github.com/freedomofpress/securedrop-client/issues/648, we will want to
         # pass the default request timeout to reply_source instead of setting it on the api object
         # directly.
-        api_client.default_request_timeout = 5
+        api_client.default_request_timeout = 0.01
         return api_client.reply_source(sdk_source, encrypted_reply, self.reply_uuid)

2. Sending a reply should not crash the app. Instead it will show up as failed in this case. Since it's a timeout it will also pause the queue.

I can confirm that the crash I initially reported in #820 (not due to the timeout, but a generic exception so harder to repro) is resolved by this, instead now I see:

2020-02-26 17:51:10,472 - securedrop_client.api_jobs.uploads:90(_set_status_to_failed) INFO: SQL error when setting reply a1e1263f-2e47-43bd-b507-807c5c9647d9 as failed, skipping: No row was found for one()

which is caused due to the DraftReply being deleted during the sync action, which we need to resolve (item 2 in the Description section).

Checklist

If these changes modify code paths involving cryptography, the opening of files in VMs or network (via the RPC service) traffic, Qubes testing in the staging environment is required. For fine tuning of the graphical user interface, testing in any environment in Qubes is required. Please check as applicable:

• I have tested these changes in the appropriate Qubes environment
• I do not have an appropriate Qubes OS workstation set up (the reviewer will need to test these changes)
• These changes should not need testing in Qubes

If these changes add or remove files other than client code, packaging logic (e.g., the AppArmor profile) may need to be updated. Please check as applicable:

• I have submitted a separate PR to the packaging repo
• No update to the packaging logic (e.g., AppArmor profile) is required for these changes
• I don't know and would appreciate guidance

[sssoleileraaa]

looks great! confirmed fixes crashing