Microblog delay should have a default value set

Along with this issue, it might be good to improve the field description in the UI to be more specific. Essentially, when a microblog gets published, the delay is effectively a syndication debounce. With a delay active, social posts via mposse will not go out until the time period defined in the delay field is expired. Every time the microblog or the subject node of that microblog is saved again, the delay timer is reset. The purpose of this is to provide a safety for indecisive content editors/managers. I may split this out as a separate issue.

I went to update the config here, but then ran into this core issue, where the field edit form cannot be saved for a list_integer field if one of the allowed values is set to 0: https://www.drupal.org/project/drupal/issues/3534125

So I think I need to find an example of setting a default value in a config/install file.

There was a nearby example right in the sent status field config install.

2 things to review here:

1. on a fresh install, the default value of mposse delay field (on microblog node) should be set to 0 (No delay)
2. same thing, but on an existing installation after applying database updates

Thanks for the review!