Enable deleting issue platform issues from the issues stream

I believe I already finished the backend work (see [test](https://github.com/getsentry/sentry/blob/4751ac2ba43d0f66af9323c60809108fa8aefe87/tests/snuba/api/endpoints/test_project_group_index.py#L1619-L1639)).

Add a bulk delete test mixing both error issues and issue platform issues. I want to see if we need to change the code handling [the countdown value](https://github.com/getsentry/sentry/blob/4909326e293b1aebc6f69c4d3dc5404b66f7dfd7/src/sentry/api/helpers/group_index/delete.py#L56-L59).

You will need to find the UI code that controls deleting issues from the issue stream and change it.

Start with tests/snuba/api/endpoints/test_project_group_index.py around the linked bulk-delete test and inspect src/sentry/api/helpers/group_index/delete.py around the countdown handling. Find the issue-stream UI code that controls deletion. Done means a bulk delete covering both error issues and issue platform issues passes, and those issue-platform issues can be deleted from the issue stream.

Written by the indexing model from the issue text.