fix(sg): append annotations not overwrite them
Created by: burmudar
Noticed a small bug. The annotations were being overwritten.
Notice the title :go: Test all (logs)
Slight note ... might be better to expand the logs link to be a full link
**:go: Test (all)** ([logs](#0181aadd-8dfb-4701-9d69-9a48cdf10ba7))
```term
[31m[1mFAIL | BranchEventSummary (0.24s)[0m
[31m[1mFAIL | BranchEventSummary/locked (0.00s)[0m
[31m[1mFAIL | github.com/sourcegraph/sourcegraph/dev/buildchecker 0.575s[0m
## Test plan
Test manually on `main-dry-run`
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