Fix grammatical error in merge_consecutive_op validation message

[Copilot]

Description

This PR fixes a grammatical error (double negative) in the error message returned by MergeConsecutiveOp.validate_input_data().

Changes

The error message previously read:

f"column_name `{name}` cannot not be a match_column."

This has been corrected to:

f"column_name `{name}` cannot be a match_column."

The double negative "cannot not" has been changed to the clearer "cannot", making the error message more professional and easier to understand.

Impact

• The error message is now grammatically correct and clearer for users
• The corresponding test in test_validator.py has been updated to match the corrected message
• All existing tests pass with the updated message
• This is a continuation of work from PR [WIP] Review the structure of the repository and make suggestions to improve the code, configuration, and practices, and code documentation. Improve the README. #1123 which aimed to improve code documentation and quality

Testing

• ✅ All 8 tests in test_merge_consecutive_op.py pass
• ✅ All 6 tests in test_validator.py pass
• ✅ All 91 tests in the remodeling operations directory pass
• ✅ Verified no other instances of this typo exist in the codebase

Original prompt

The agent did not complete the request in PR #1123 before it was merged. Please continue

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