ci: run sysbench against 2.10 branch

The '2.8' branch is no longer supported. So let's switch to '2.10'.

NO_DOC=ci
NO_TEST=ci
NO_CHANGELOG=ci

(cherry picked from commit b212ceeb)

.github/workflows/perf_sysbench.yml

@@ -28,7 +28,7 @@ jobs:
       fail-fast: false
       max-parallel: 1
       matrix:
-        branch: [ 'master', '2.8' ]
+        branch: [ 'master', '2.10' ]
 
     steps:
       - name: Checkout tarantool