[fix][broker] Fix duplicate increment of ADD_OP_COUNT_UPDATER in OpAddEntry

[3pacccccc]

Motivation

Currently, when adding a message to a ledger, ManagedLedgerImpl.ADD_OP_COUNT_UPDATER is incremented twice:

1. First increment occurs in createOpAddEntryNoRetainBuffer() when creating the OpAddEntry
2. Second increment occurs in OpAddEntry.initiate()

This double increment leads to incorrect operation counting and potential metric inaccuracies.
here's the example I've tested on my local.

Modifications

• Changed the second occurrence in OpAddEntry.initiate() from incrementAndGet() to get() to prevent duplicate counting
• Added a test case testAddOpCountWithMessageAdd() to verify the correct increment behavior

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#11

[3pacccccc]

since I got some problems when rebase to master in #24502, so I close that PR and open a new one, please take a look again. thank you
@dao-jun @nodece @Technoboy-