fix: rebalance over recycle on only tenant config conn change

[ferhatelmas]

What kind of change does this PR introduce?

Bug fix (performance improvement)

What is the current behavior?

On only max connections change for tenant config, pool is recycled which creates unnecessary connection/socket churn.

What is the new behavior?

Mutates the pool in place, increases are immediate and decreases are handled by idle timeout.

Additional context

Related to #1125 - prior approach
Related to #1096 - already has this approach

[Copilot]

Pull request overview

This PR adjusts multitenant DB pool handling so that tenant config changes affecting only maxConnections no longer recycle (destroy/recreate) the cached pool, but instead rebalance it in place to reduce connection/socket churn while still applying increases immediately and letting decreases drain via normal idle behavior.

Changes:

• Update onTenantConfigChange to call PoolManager.rebalance(...) when only maxConnections changes (and still destroy(...) on endpoint/pool-mode changes).
• Add a targeted PoolManager.rebalance(tenantId, options) API and remove the previous recycle(...) API.
• Update/add tests to validate rebalance behavior and the removal of recycle.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/test/tenant.test.ts	Updates tenant-config change tests to expect rebalance (not recycle) on maxConnections changes.
src/internal/database/tenant.ts	Switches max-connection-change handling from pool recycle to in-place rebalance; removes unused recycle settings builder.
src/internal/database/pool.ts	Adds PoolManager.rebalance forwarding method and removes PoolManager.recycle.
src/internal/database/pool.test.ts	Adds coverage for PoolManager.rebalance forwarding and asserts recycle is no longer part of the API.

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[coveralls]

Coverage Report for CI Build 27134423353

Coverage decreased (-0.009%) to 76.438%

Details

• Coverage decreased (-0.009%) from the base build.
• Patch coverage: 4 of 4 lines across 2 files are fully covered (100%).
• No coverage regressions found.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	11030
Covered Lines:	8861
Line Coverage:	80.34%
Relevant Branches:	6460
Covered Branches:	4508
Branch Coverage:	69.78%
Branches in Coverage %:	Yes
Coverage Strength:	369.09 hits per line

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💛 - Coveralls

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.