[fix](packed-file) fix some case for packed small files

[liaoxin01]

What problem does this PR solve?

Issue Number: close #xxx

Related PR: #57770

Problem Summary:

Release note

None

Check List (For Author)

• Test

  • Regression test
  • Unit Test
  • Manual test (add detailed scripts or steps below)
  • No need to test or manual test. Explain why:
    • This is a refactor/code format and no logic has been changed.
    • Previous test can cover this change.
    • No code files have been changed.
    • Other reason

• Behavior changed:

  • No.
  • Yes.

• Does this need documentation?

  • No.
  • Yes.

Check List (For Reviewer who merge this PR)

• Confirm the release note
• Confirm test cases
• Confirm document
• Add branch pick label

[Thearas]

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1. What problem was fixed (it's best to include specific error reporting information). How it was fixed.
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4. Which code was refactored and why was this part of the code refactored?
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[liaoxin01]

run buildall

[Copilot]

Pull request overview

This PR refactors the small file packing feature by renaming "merge_file" terminology to "packed_file" across multiple test files. The change improves naming consistency and clarity by using "packed_file" instead of "merge_file" for the feature that packs small files together. The refactoring updates function names, variable names, configuration keys, metric names, and documentation comments.

Key changes:

• Updated configuration key from enable_merge_file to enable_packed_file
• Renamed metrics from merge_file_total_small_file_num to packed_file_total_small_file_num
• Updated all function names, variable names, and comments to use "packed_file" terminology

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
test_packed_file_with_group_commit.groovy	Updated function names, variables, config keys, metric names, and comments from "merge_file" to "packed_file" terminology
test_packed_file_query_with_table_drop.groovy	Updated configuration key from enable_merge_file to enable_packed_file
test_packed_file_mixed_load.groovy	Updated function names, variables, metric names, and comments from "merge_file" to "packed_file" terminology
test_packed_file_concurrent_load.groovy	Updated function names, variables, metric names, and comments from "merge_file" to "packed_file" terminology

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[Copilot]

The table name still uses the old "test_merge_file_" prefix. For consistency with the refactoring from "merge_file" to "packed_file", this should be renamed to "test_packed_file_with_group_commit".

Suggested change

	def tableName = "test_merge_file_with_group_commit"
	def tableName = "test_packed_file_with_group_commit"

[liaoxin01]

run buildall

[github-actions]

PR approved by at least one committer and no changes requested.

[github-actions]

PR approved by anyone and no changes requested.