[ISSUE #8092] Fixed non-idempotent test

[kaiyaok2]

Which Issue(s) This PR Fixes

Fixes #8092

Brief Description

The test org.apache.rocketmq.filter.FilterSpiTest#testRegister is non-idempotent, as it passes in the first run but fails in the second run in the same JVM. The test fails in subsequent runs in the same environment because it registers a NothingFilter without unregistering it. The repeated run will then throw a Filter already exist error. A fix is recommended as unit tests shall be idempotent, and state pollution shall be mitigated so that newly introduced tests do not fail in the future due to polluted shared states.

Failure Message in the 2nd Run:

java.lang.IllegalArgumentException: Filter spi type(Nothing) already exist!
	at org.apache.rocketmq.filter.FilterFactory.register(FilterFactory.java:44)
	at org.apache.rocketmq.filter.FilterSpiTest.testRegister(FilterSpiTest.java:53)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)

How Did You Test This Change?

Unset NothingFilter before exiting the test. All tests pass and are idempotent after the fix.

[cserwen]

rebase with the latest develop branch which has fixed some errors of check @kaiyaok2

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 42.86%. Comparing base (1a2fc17) to head (9db1d3f).
Report is 1 commits behind head on develop.

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #8093      +/-   ##
=============================================
+ Coverage      42.84%   42.86%   +0.02%     
- Complexity     10351    10362      +11     
=============================================
  Files           1270     1270              
  Lines          88690    88690              
  Branches       11399    11399              
=============================================
+ Hits           37998    38020      +22     
+ Misses         45993    45979      -14     
+ Partials        4699     4691       -8     

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