[ZEPPELIN-6221] Optimize Neo4jCypherInterpreterTest performance by reusing interpreter instance

[jongheon1]

What is this PR for?

This PR optimizes the performance of Neo4jCypherInterpreterTest by eliminating redundant interpreter initialization.
Currently, each test method creates and closes a new Neo4jCypherInterpreter instance, which introduces unnecessary overhead when running against a Neo4j Testcontainer.
By using @testinstance(TestInstance.Lifecycle.PER_CLASS) and moving setup to @BeforeAll, we reduce initialization from 11 times to 1 time, improving test execution time.

What type of PR is it?

Improvement

Todos

• - Use @testinstance(TestInstance.Lifecycle.PER_CLASS) annotation
• - Move interpreter setup from @beforeeach to @BeforeAll
• - Make interpreter and context static fields
• - Verify all tests still pass

What is the Jira issue?

• https://issues.apache.org/jira/browse/ZEPPELIN-6221

How should this be tested?

1. Run the Neo4jCypherInterpreterTest suite: mvn test -Dtest=Neo4jCypherInterpreterTest
2. Verify all 11 tests pass successfully
3. Confirm test execution time is reduced compared to the previous implementation

Screenshots (if appropriate)

N/A

Questions:

• Does the licenses files need update? No.
• Is there breaking changes for older versions? No.
• Does this needs documentation? No.

[Reamer]

I have noticed a difference.
Before:

After:

In my eyes, 2 seconds does not justify changing the long-established standard from @TestInstance(TestInstance.Lifecycle.PER_METHOD) to @TestInstance(TestInstance.Lifecycle.PER_CLASS), therefore I reject the change. If another maintainer sees this differently, they are welcome to open this PR again.