[fix][test] Fix flaky EntryCacheManagerTest.simple

[3pacccccc]

Fixes #24608

motivation

this test was flaky due to
line108 in EntryCacheManagerTest.java of current master branch
already triggered cache eviction, so sometimes the eviction is over, sometimes not, cause this flaky.

Modifications

1. Removed one entry insertion (EntryImpl.create(2, 2, new byte[1]) to:
   • Ensure predictable cache eviction timing
   • Maintain test's original purpose of verifying eviction logic
2. Updated all affected assertions to match the new expected cache sizes:
   • Reduced expected sizes by 1 across all assertions
   • Maintained consistent state validation throughout test flow

Verifying this change

• Make sure that the change passes the CI checks.

(Please pick either of the following options)

This change is a trivial rework / code cleanup without any test coverage.

(or)

This change is already covered by existing tests, such as (please describe tests).

(or)

This change added tests and can be verified as follows:

(example:)

• Added integration tests for end-to-end deployment with large payloads (10MB)
• Extended integration test for recovery after broker failure

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository: 3pacccccc#21