[skip e2e] Modify kafka configuration for nightly (#20237)

Signed-off-by: NBinbin Lv <binbin.lv@zilliz.com>
Signed-off-by: NBinbin Lv <binbin.lv@zilliz.com>

tests/scripts/values/kafka.yaml

 kafka:
   enabled: true
+  defaultReplicationFactor: 2
 pulsar:
   enabled: false
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