fix: don't add release team as reviewer for backports (#2657)

Clone of the Cody PR #6136, so that we don't have failing backports

## Test plan
Tested on the [Cody repo](sourcegraph/cody#6136)
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.github/workflows/backport.yml

@@ -25,3 +25,4 @@ jobs:
         with:
           github_token: ${{ secrets.BACKPORT_GITHUB_TOKEN }}
           label_pattern: '^backport (?<base>jb-v\d+\.\d+\.x)$'
+          team_reviews: ''