Rebreak: Fix meta dedent segment order

[keraion]

Brief summary of the change made

This fixes how rebreak recombines moved elements for the "Leading Tricky Case", namely dedent segments.

• Fixes ST06 + LT04 corrupts SQL (commas are erroneously added or removed) #4882
• Fixes Wrong formatting for Snowflake caused by ST06 #5913

This also fixes when a rebreak doesn't have an anchor point and attempts to find the next element with segments.

• Fixes LT04: Unexpected exception when unable to find a creation anchor #5973

Are there any other side effects of this change that we should be aware of?

None

Pull Request checklist

• Please confirm you have completed any of the necessary steps below.

• Included test cases to demonstrate any code changes, which may be one or more of the following:

  • .yml rule test cases in test/fixtures/rules/std_rule_cases.
  • .sql/.yml parser test cases in test/fixtures/dialects (note YML files can be auto generated with tox -e generate-fixture-yml).
  • Full autofix test cases in test/fixtures/linter/autofix.
  • Other.

• Added appropriate documentation for the change.

• Created GitHub issues for any relevant followup/future enhancements if appropriate.

[github-actions]

Coverage Results ✅

Name    Stmts   Miss  Cover   Missing
-------------------------------------
TOTAL   17828      0   100%

225 files skipped due to complete coverage.

[coveralls]

coverage: 99.985%. remained the same
when pulling 7d497e7 on keraion:LT04_ST06_complex_interaction
into e962fc1 on sqlfluff:main.

[WittierDinosaur]

Hitting 3 issues in 1, great job!