[fix](cache) enhance cache key computation by removing comments and trimming SQL input

[Baymine]

What problem does this PR solve?

Issue Number: close #xxx

Related PR: #xxx

Problem Summary:

• Currently, the SQL cache system in Doris may miss cache hits due to semantically identical queries being treated as different because of:
  • Extra whitespace characters in the SQL query
  • SQL comments that don't affect the query execution
• For example, these queries are semantically identical but would generate different cache keys:

  SELECT * FROM table;
  -- Same query with comments and extra spaces
  /* Comment */  SELECT   *   FROM   table  ;

• This PR improves the SQL cache hit rate by:
  • Trimming whitespace from SQL queries
  • Removing SQL comments before calculating the cache key MD5
• This ensures that queries that are semantically identical but differ only in whitespace or comments will now hit the same cache entry, improving cache efficiency and reducing unnecessary query executions

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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Please clearly describe your PR:

1. What problem was fixed (it's best to include specific error reporting information). How it was fixed.
2. Which behaviors were modified. What was the previous behavior, what is it now, why was it modified, and what possible impacts might there be.
3. What features were added. Why was this function added?
4. Which code was refactored and why was this part of the code refactored?
5. Which functions were optimized and what is the difference before and after the optimization?