MongoDB logstore index is suboptimal

Hello

The MongoDB logstore module uses a suboptimal indexes, thus the query uses a BasicCursor. Here is a patch creating an index that will make the query use a BtreeCursor exclusively.

I don't know what we should do with the old "time_idx" index. Detect it and remove it, mention it in the documentation, write a script in contrib that removes it, leave it in the database?