[backend] feat: reset XTM Hub registration when platform is not found (#4441)

[Kroustille]

Proposed changes

• reset registration data when platform is not found on the hub
• refactor how connectivity lost email is handled

Testing Instructions

1. register platform on the hub
2. remove platform in the hub
3. check that registration is removed after connectivity check

Related issues

• [XTMH] reset registration data when platform is not found in the hub #4441
• Admins of all the staging training l instances get spammed by emails FiligranHQ/xtm-hub#1286

Checklist

• I consider the submitted work as finished
• I tested the code for its functionality
• I wrote test cases for the relevant uses case
• I added/update the relevant documentation (either on github or on notion)
• Where necessary I refactored code to improve the overall quality
• For bug fix -> I implemented a test that covers the bug

Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 50.11%. Comparing base (b361d2d) to head (92bf55f).
⚠️ Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
...a/io/openaev/xtmhub/XtmHubConnectivityService.java	40.00%	5 Missing and 1 partial ⚠️
.../src/main/java/io/openaev/xtmhub/XtmHubClient.java	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #4442      +/-   ##
============================================
- Coverage     50.13%   50.11%   -0.02%     
+ Complexity     3639     3637       -2     
============================================
  Files           896      896              
  Lines         26560    26576      +16     
  Branches       1989     1991       +2     
============================================
+ Hits          13316    13319       +3     
- Misses        12445    12457      +12     
- Partials        799      800       +1     

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[savacano28]

Tested OK!