Refactored KapuaFileUtilsTest

[Coduz]

This PR refactors KapuaFIleUtilsTest to make it better.

This is an integration of PR #3639

Related Issue
This PR integrates changes in #3639

Description of the solution adopted
Improved tests

Screenshots
None

Any side note on the changes made
None

[codecov]

Codecov Report

Merging #3641 (384c309) into develop (a5600c1) will decrease coverage by 19.46%.
The diff coverage is n/a.

❗ Current head 384c309 differs from pull request most recent head 53b17a7. Consider uploading reports for the commit 53b17a7 to get more accurate results

@@              Coverage Diff               @@
##             develop    #3641       +/-   ##
==============================================
- Coverage      34.00%   14.53%   -19.47%     
+ Complexity       122        8      -114     
==============================================
  Files           1668     1668               
  Lines          31987    31987               
  Branches        2634     2634               
==============================================
- Hits           10877     4650     -6227     
- Misses         20552    26928     +6376     
+ Partials         558      409      -149     

Impacted Files	Coverage Δ
...rc/main/java/org/eclipse/kapua/KapuaException.java	0.00% <0.00%> (-100.00%)	⬇️
...c/main/java/org/eclipse/kapua/KapuaErrorCodes.java	0.00% <0.00%> (-100.00%)	⬇️
.../java/org/eclipse/kapua/commons/util/Payloads.java	0.00% <0.00%> (-100.00%)	⬇️
...in/java/org/eclipse/kapua/broker/BrokerDomain.java	0.00% <0.00%> (-100.00%)	⬇️
...java/org/eclipse/kapua/commons/util/ClassUtil.java	0.00% <0.00%> (-100.00%)	⬇️
...ain/java/org/eclipse/kapua/event/ServiceEvent.java	0.00% <0.00%> (-100.00%)	⬇️
...n/java/org/eclipse/kapua/broker/BrokerDomains.java	0.00% <0.00%> (-100.00%)	⬇️
...va/org/eclipse/kapua/commons/util/SystemUtils.java	0.00% <0.00%> (-100.00%)	⬇️
...n/java/org/eclipse/kapua/model/domain/Actions.java	0.00% <0.00%> (-100.00%)	⬇️
.../java/org/eclipse/kapua/message/KapuaPosition.java	0.00% <0.00%> (-100.00%)	⬇️
... and 693 more