Change vmsnapshot.max configuration to be dynamic

[lucas-a-martins]

Description

Currently, the configuration vmsnapshot.max isn't dynamic, and it is necessary to restart the Management Server after changing the configuration's value.

This PR intends to change the vmsnapshot.max config to the new ConfigKey standard for dynamic configurations.

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)
• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (improves an existing feature and functionality)
• Cleanup (Code refactoring and cleanup, that may add test cases)
• build/CI
• test (unit or integration test code)

Feature/Enhancement Scale or Bug Severity

Feature/Enhancement Scale

• Major
• Minor

Screenshots (if appropriate):

How Has This Been Tested?

To validate the changes, I performed the following steps without restarting the Management Server:

1. Changed the vmsnapshot.max value to 2;
2. Tried to take 3 VM snapshots, but as expected, an exception was thrown on the 3rd snapshot;
3. Changed the vmsnapshot.max value to 3;
4. Tried to take the 3rd snapshot again, and it was created successfully;
5. Tried to take a 4th snapshot and got the same exception.

[DaanHoogland]

clgtm

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 15.78%. Comparing base (019f2c6) to head (00492c0).

Files with missing lines	Patch %	Lines
...a/com/cloud/vm/snapshot/VMSnapshotManagerImpl.java	75.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##               main    #9883     +/-   ##
===========================================
  Coverage     15.78%   15.78%             
- Complexity    12564    12566      +2     
===========================================
  Files          5627     5627             
  Lines        492250   492250             
  Branches      61405    62693   +1288     
===========================================
+ Hits          77710    77718      +8     
+ Misses       406066   406058      -8     
  Partials       8474     8474             

Flag	Coverage Δ
uitests	4.04% <ø> (ø)
unittests	16.60% <80.00%> (+<0.01%)	⬆️

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