[#3388]Reset nacos roles, permissions during reloading role info from database

[yanjunnf]

Please do not create a Pull Request without creating an issue first.

What is the purpose of the change

#3388

Brief changelog

We should rest nacos roles, permissions when reloading role info from database. For some scenarios, some roles and permission may be removed by administrator.

Verifying this change

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[chuntaojun]

使用volatile修饰，确保线程间可见，或者使用AtomicReference

[yanjunnf]

Already added.

[yanjunnf]

Checked the failed build log below, looks like this error is nothing to do with code changes.

Tests run: 33, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 222.362 sec <<< FAILURE! - in com.alibaba.nacos.test.config.ConfigAPI_CITCase
nacos_addListener_1(com.alibaba.nacos.test.config.ConfigAPI_CITCase) Time elapsed: 25.031 sec <<< ERROR!
org.junit.runners.model.TestTimedOutException: test timed out after 25000 milliseconds
at app//com.alibaba.nacos.test.config.ConfigAPI_CITCase.nacos_addListener_1(ConfigAPI_CITCase.java:372)