test: add comprehensive unit tests for RaftRegistryServiceImpl (#7779)

Author: WangzJi

changes/en-us/2.x.md

@@ -154,6 +154,7 @@ Add changes here for all PR submitted to the 2.x branch.
 - [[#7727](https://github.com/apache/incubator-seata/pull/7727)] add some UT for compatible module
 - [[#7803](https://github.com/apache/incubator-seata/pull/7803)] Fix flakiness in `DataCompareUtilsTest` caused by non-deterministic Map key iteration order.
 - [[#7804](https://github.com/apache/incubator-seata/pull/7804)] fix testXARollbackWithResourceLock() to ensure ci runs normally
+- [[#7779](https://github.com/apache/incubator-seata/pull/7779)] improve unit tests for RaftRegistryServiceImpl
 - [[#7801](https://github.com/apache/incubator-seata/pull/7801)] Fix non-deteriministic in JsonParserWrapTest#testToJSONString due to key order
 - [[#7800](https://github.com/apache/incubator-seata/pull/7800)] fix non-deterministic in StringUtilsTest#testToStringAndCycleDependency
 - [[#7802](https://github.com/apache/incubator-seata/pull/7802)] Fix non-deterministic in `ConnectionContextProxyTest`.

changes/zh-cn/2.x.md

@@ -153,6 +153,7 @@
 - [[#7727](https://github.com/apache/incubator-seata/pull/7727)] 为 compatible 模块添加单测
 - [[#7803](https://github.com/apache/incubator-seata/pull/7803)] 修复 `DataCompareUtilsTest` 中因键迭代顺序不稳定导致的测试用例间歇性失败问题。
 - [[#7804](https://github.com/apache/incubator-seata/pull/7804)] 修复 testXARollbackWithResourceLock() 以确保 CI 正常运行
+- [[#7779](https://github.com/apache/incubator-seata/pull/7779)] 提高 RaftRegistryServiceImpl 单测覆盖
 - [[#7801](https://github.com/apache/incubator-seata/pull/7801)] 修复 `JsonParserWrapTest.testToJSONString` 因字段顺序不稳定导致的测试用例间歇性失败问题
 - [[#7800](https://github.com/apache/incubator-seata/pull/7800)] 修复 `StringUtilsTest.testToStringAndCycleDependency` 因反射字段顺序不稳定导致的测试用例间歇性失败问题
 - [[#7802](https://github.com/apache/incubator-seata/pull/7802)] 修复 `ConnectionContextProxyTest` 中锁键顺序不稳定导致的测试用例间歇性失败问题。