Use IsNullOrEmpty instead null-check in AuditLogs Repositories

[enisn]

Description

Resolves https://github.com/volosoft/volo/issues/15999

Since empty values are considered as filtering options for strings, Audit logs repositories will check if it's NullOrEmpty, instead only null-check.

⚠️ Breaking Change Note

Warning: This may cause some behavioral changes if you used this repository methods by your own

Checklist

• I fully tested it as developer / designer and created unit / integration tests
• I documented it (or no need to document or I will create a separate documentation issue)

How to test it?

Please describe how this can be tested by the test engineers if it is not already explicit - or remove this section if no need to description.

[codecov]

Codecov Report

Attention: 42 lines in your changes are missing coverage. Please review.

Comparison is base (b049d07) 51.58% compared to head (c079cdc) 51.58%.
Report is 22 commits behind head on rel-8.0.

Files	Patch %	Lines
...dict/Applications/AbpOpenIddictApplicationStore.cs	55.35%	23 Missing and 2 partials ⚠️
...enIddict/Tokens/EfCoreOpenIddictTokenRepository.cs	14.28%	6 Missing ⚠️
...penIddict/Tokens/MongoOpenIddictTokenRepository.cs	25.00%	6 Missing ⚠️
...o/Abp/OpenIddict/Tokens/AbpOpenIddictTokenStore.cs	40.00%	3 Missing ⚠️
...ng/Building/TemplateProjectBuildPipelineBuilder.cs	0.00%	1 Missing ⚠️
...ct/Applications/OpenIddictApplicationExtensions.cs	92.30%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           rel-8.0   #18504   +/-   ##
========================================
  Coverage    51.58%   51.58%           
========================================
  Files         3073     3073           
  Lines        96910    96910           
  Branches      7715     7715           
========================================
  Hits         49987    49987           
  Misses       45392    45392           
  Partials      1531     1531           

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