Add option to drop datastore if there is an error on post_import

[janette]

RE: 22023

Describe your changes

Adds a config option to drop the datastore table if the post_import queue reports an error

QA Steps

• See Jira

Checklist before requesting review

If any of these are left unchecked, please provide an explanation

• I have updated or added tests to cover my code
• I have updated or added documentation

[chri5tia]

Test drop logic on post-import error.

1. Verify that datastoreService->drop() is called when a post-import error occurs, and drop_config is enabled.
   Test log messages on success.

2. Verify that a notice is logged when the datastore is successfully dropped.
   Test exception handling.

3. Verify that errors are logged if datastoreService->drop() throws an exception.
   Test no drop when drop_config is disabled.

4. Verify that the drop() method is not called when drop_config is disabled, even if there's a post-import error.

@janette I had to change the way 'datastore.settings' is retrieved so that it comes from the config factory so it can be stored as a config object for the test. Let me know if this is wrong and/or messes anything up.

[rovcase]

Hello wowee good stuff (very helpful to look into the test files too). Just one minor possibly redundant question as well as one piece of code cleanup. Thanks!

[rovcase]

LGTM, thanks!