Enabling/disabling kapua-sys user feature

[gbarbon]

This PR allows enabling/disabling the kapua-sys user.

Related Issue
This PR fixes/closes #3091

Description of the solution adopted
The check that prevents the update of the kapua-sys user status has been removed.

Screenshots
n/a

Any side note on the changes made
n/a

[codecov]

Codecov Report

Merging #3092 into develop will decrease coverage by 0.93%.
The diff coverage is 0.00%.

@@              Coverage Diff              @@
##             develop    #3092      +/-   ##
=============================================
- Coverage      60.82%   59.89%   -0.94%     
+ Complexity      2598     2516      -82     
=============================================
  Files           1110     1110              
  Lines          23267    23267              
  Branches        2006     2006              
=============================================
- Hits           14153    13936     -217     
- Misses          8157     8388     +231     
+ Partials         957      943      -14     

Impacted Files	Coverage Δ	Complexity Δ
...e/kapua/service/user/internal/UserServiceImpl.java	26.78% <0.00%> (-33.04%)	14.00 <0.00> (-15.00)
...rvice/endpoint/internal/EndpointInfoQueryImpl.java	0.00% <0.00%> (-100.00%)	0.00% <0.00%> (-1.00%)
.../endpoint/internal/EndpointInfoListResultImpl.java	0.00% <0.00%> (-100.00%)	0.00% <0.00%> (-1.00%)
...pua/service/endpoint/internal/EndpointInfoDAO.java	0.00% <0.00%> (-85.72%)	0.00% <0.00%> (-5.00%)
...ndpoint/internal/EndpointEntityManagerFactory.java	0.00% <0.00%> (-83.34%)	0.00% <0.00%> (-3.00%)
...ice/endpoint/internal/EndpointInfoServiceImpl.java	0.00% <0.00%> (-74.51%)	0.00% <0.00%> (-18.00%)
...ice/endpoint/internal/EndpointInfoCreatorImpl.java	0.00% <0.00%> (-73.69%)	0.00% <0.00%> (-9.00%)
...ua/service/endpoint/internal/EndpointInfoImpl.java	0.00% <0.00%> (-62.07%)	0.00% <0.00%> (-10.00%)
...ice/endpoint/internal/EndpointInfoFactoryImpl.java	0.00% <0.00%> (-33.34%)	0.00% <0.00%> (-3.00%)
... and 26 more