Ability to stop indexing a repo

> [!NOTE]
> Migrated from [augurlabs/augur#2923](https://github.com/augurlabs/augur/issues/2923)
> Originally opened by `@GregSutcliffe` on 2024-10-08

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**Is your feature request related to a problem? If so, please describe the problem:**
I have a specific but changing list of repos I need to track data on, and a limited number of API keys. Accordingly, I would like to be able to stop indexing repos in some manner.

I've had a look through the docs, and I can't see anything in the CLI or UI that allows me to do this, or to delete the data for a repo that may no longer be relevant to me.

**Potential solutions:**
The obvious solution would be to add a command to the `augur db` since that already has commands for `add-repos` and for listing groups. A UI solution is nice but not essential, I think.

**Additional context:**
This is actually relevant even for a day-1 fresh install, as Augur starts up with a pre-seeded set of repos to index. While this makes sense to give it something to operate on, at some point in time the user is likely to want to stop indexing those example repos.