wip: enhance: Support merge existing partitionStats with the new

[wayblink]

No description provided.

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: wayblink
To complete the pull request process, please assign jiaoew1991 after the PR has been reviewed.
You can assign the PR to them by writing /assign @jiaoew1991 in a comment when ready.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• internal/datacoord/OWNERS
• internal/storage/OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[mergify]

@wayblink Thanks for your contribution. Please submit with DCO, see the contributing guide https://github.com/milvus-io/milvus/blob/master/CONTRIBUTING.md#developer-certificate-of-origin-dco.

[mergify]

@wayblink

Invalid PR Title Format Detected

Your PR submission does not adhere to our required standards. To ensure clarity and consistency, please meet the following criteria:

1. Title Format: The PR title must begin with one of these prefixes:

• feat: for introducing a new feature.
• fix: for bug fixes.
• enhance: for improvements to existing functionality.
• test: for add tests to existing functionality.
• doc: for modifying documentation.
• auto: for the pull request from bot.

2. Description Requirement: The PR must include a non-empty description, detailing the changes and their impact.

Required Title Structure:

[Type]: [Description of the PR]

Where Type is one of feat, fix, enhance, test or doc.

Example:

enhance: improve search performance significantly 

Please review and update your PR to comply with these guidelines.