search-blitz: renable mono_rev_symbol_small
Created by: keegancsmith
This reverts commit 5929cb6887733af4df3161223899e46447837c8c. We disabled this since it was causing the symbols service to be unresponsive.
Test Plan: once landed we will deploy a new version and monitor the impact. We expect after 15min that the query will start to succeed (cold start time).
Fixes https://github.com/sourcegraph/sourcegraph/issues/28457