trpc-registry: migrate tests from JUnit 4 + PowerMock to JUnit 5 + Mockito

[drow931]

trpc-registry: migrate tests from JUnit 4 + PowerMock to JUnit 5 + Mockito

Migrate all test classes in trpc-registry module from JUnit 4 with
PowerMock to JUnit 5 with Mockito, improving test maintainability
and compatibility with modern Java versions.

Changes across all submodules:

Common Changes:

• Replace JUnit 4 annotations with JUnit 5 equivalents:
  • @before -> @beforeeach
  • @after -> @AfterEach
  • @RunWith -> @ExtendWith(MockitoExtension.class)
• Replace Assert.* with Assertions.*
• Replace PowerMock static mocking with Mockito.mockStatic()
• Replace Whitebox.invokeMethod() with Java reflection API
• Update pom.xml files to add mockito-junit-jupiter dependency

Affected Modules:

• trpc-registry-api (8 test files)
• trpc-registry-consul (6 test files)
• trpc-registry-nacos (4 test files)
• trpc-registry-open-polaris (4 test files)
• trpc-registry-zookeeper (2 test files)

Key Technical Changes:

1. Static mocking pattern:

   • Before: PowerMockito.mockStatic(SomeClass.class)
   • After: MockedStatic mock = Mockito.mockStatic(SomeClass.class)
     with proper cleanup in @AfterEach

2. Private method invocation:

   • Before: Whitebox.invokeMethod(obj, "method", args)
   • After: Method m = Class.getDeclaredMethod("method", types);
     m.setAccessible(true);
     m.invoke(obj, args);

3. Assertions:

   • Before: Assert.assertEquals(expected, actual)
   • After: Assertions.assertEquals(expected, actual)

Total: 26 files changed, 349 insertions(+), 304 deletions(-)