refactor: remove in-place union operator |= UI test cases.

[Peefy]

1. Does this PR affect any open issues?(Y/N) and add issue references (e.g. "fix #123", "re #123".):

• N
• Y

re: #143

Remove the |= operator to configure the semantics of in-place merge, and use the : merge attribute operator instead
Remove or modify test cases related to |= operator

2. What is the scope of this PR (e.g. component or file name):

3. Provide a description of the PR(e.g. more details, effects, motivations or doc link):

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Other

4. Are there any breaking changes?(Y/N) and describe the breaking changes(e.g. more details, motivations or doc link):

• N
• Y

Motivations: Unify the concept of "configuration unification" in KCL, remove redundant operators. More info ref: https://kusionstack.io/docs/reference/lang/lang/tour#%E9%85%8D%E7%BD%AE%E6%93%8D%E4%BD%9C

5. Are there test cases for these changes?(Y/N) select and add more details, references or doc links:

• Unit test
• Integration test
• Benchmark (add benchmark stats below)
• Manual test (add detailed scripts or steps below)
• Other

Remove or modify test cases related to |= operator in the tests folder.

6. Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[coveralls]

Pull Request Test Coverage Report for Build 2865250775

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 6 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.02%) to 59.563%

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Files with Coverage Reduction	New Missed Lines	%
kclvm/sema/src/resolver/calculation.rs	6	62.87%

Totals
Change from base Build 2861308171:	-0.02%
Covered Lines:	22385
Relevant Lines:	37582

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💛 - Coveralls

[ldxdl]

LGTM

[He1pa]

LGTM