[fix][broker] Fix incorrect bundle split count metric

[Shawyeok]

Motivation

Suppose there is a non-partitioned topic has more than 1000 producers (1000 is loadBalancerNamespaceBundleMaxSessions default value), pulsar_lb_bundles_split_count metric will increase constantly due to corresponding bundle reached maxBundleSessions, even the bundle range is 1 (upper - lower) that actually will skip this bundle.

Modifications

Only increase pulsar_lb_bundles_split_count metric if bundle splits succeed.

Verifying this change

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

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 binary protocol
• The REST endpoints
• The admin CLI options
• Anything that affects deployment

Documentation

• doc

Matching PR in forked repository

PR in forked repository: Shawyeok#2

[github-actions]

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- [ ] `doc` <!-- Your PR contains doc changes -->
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[Shawyeok]

@hangc0276 Please take a review, thanks.

[Shawyeok]

/pulsarbot rerun-failure-checks

[Shawyeok]

/pulsarbot rerun-failure-checks

[codelipenghui]

The change looks good to me.