TRUNK-6706: Disable hibernate.generate_statistics by default

[Janani-Balasooriya]

Description of what I changed

Changed the default value of hibernate.generate_statistics in api/src/main/resources/hibernate.default.properties from true to false. Statistics generation maintains counters on every query, entity, collection, and cache operation, and the only consumer in core is a shutdown-time debug log dump, so this default was adding overhead for data that's almost never read.

No code changes were needed to preserve explicit overrides:
HibernateContextDAO.mergeDefaultRuntimeProperties() already only applies a default when the key isn't already present in the user's runtime properties, so anyone setting hibernate.generate_statistics=true themselves will have that value preserved.

Added two unit tests to ContextDAOTest.java:

• should_defaultGenerateStatisticsToFalse()
• should_notOverrideExplicitGenerateStatisticsSetting()

Note: I noticed three tests in ContextTest.java check cache eviction using Hibernate's statistics counter, which no longer updates by default after this change. Flagging in case a follow-up is wanted, happy to help fix if so.

I noticed this ticket is labeled backport. Should this fix also be applied to older maintained branches, or is that handled separately by the team?

Issue I worked on

see https://issues.openmrs.org/browse/TRUNK-6706

Checklist: I completed these to help reviewers :)

• My IDE is configured to follow the code style of this project.

  No? Unsure? -> configure your IDE, format the code and add the changes with git add . && git commit --amend

• I have added tests to cover my changes. (If you refactored
  existing code that was well tested you do not have to add tests)

  No? -> write tests and add them to this commit git add . && git commit --amend

• I ran ./mvnw clean package right before creating this pull request and
  added all formatting changes to my commit.

  No? -> execute above command

• All new and existing tests passed.

  No? -> figure out why and add the fix to your commit. It is your responsibility to make sure your code works.

• My pull request is based on the latest changes of the master branch.

  No? Unsure? -> execute command git pull --rebase upstream master

[dkayiwa]

@claude review

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.58%. Comparing base (c21a7cb) to head (13ff9a6).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6354      +/-   ##
============================================
+ Coverage     59.45%   59.58%   +0.13%     
- Complexity     9555     9567      +12     
============================================
  Files           731      731              
  Lines         38399    38399              
  Branches       5598     5598              
============================================
+ Hits          22829    22879      +50     
+ Misses        13532    13479      -53     
- Partials       2038     2041       +3     

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[jwnasambu]

@claude review