fix: snuba subscription test

[lynnagara]

fix test for https://github.com/getsentry/snuba/pull/5868

the events topic needs to exist for subscriptions to work

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 77.95%. Comparing base (682c237) to head (c5535d7). Report is 282 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #70809      +/-   ##
==========================================
- Coverage   80.01%   77.95%   -2.07%     
==========================================
  Files        6504     6508       +4     
  Lines      290767   290210     -557     
  Branches    50119    50221     +102     
==========================================
- Hits       232662   226228    -6434     
- Misses      57668    57677       +9     
- Partials      437     6305    +5868     

see 1604 files with indirect coverage changes