Select dispatch-wheel-builds octo-sts policy per source repo (#24245)

The dispatch job hardcoded the integrations-core.dispatch-wheel-builds octo-sts
policy, so releases driven from marketplace or integrations-extras requested a
policy whose subject/repository claims never match the caller, yielding a 403
permission denied. Derive the policy name from source-repo so each repo uses its
own dispatch-wheel-builds trust policy.

Author: dkirov-dd

.github/workflows/release-dispatch.yml

@@ -156,7 +156,7 @@ jobs:
         uses: DataDog/dd-octo-sts-action@08f2144903ced3254a3dafec2592563409ba2aa0 # v1.0.1
         with:
           scope: DataDog/agent-integration-wheels-release
-          policy: integrations-core.dispatch-wheel-builds
+          policy: ${{ inputs.source-repo || 'integrations-core' }}.dispatch-wheel-builds
 
       - name: Dispatch release
         uses: peter-evans/repository-dispatch@ff45666b9427631e3450c54a1bcbee4d9ff4d7c0 # v3.0.0