PipelineIndentationStyle: Fix edge case where pipeline was incorrectly detected to span mutliple lines due to backticks in the command leading up to the pipeline

[bergmeister]

PR Summary

Fixes #1311 by refining the logic to determine if a pipeline spans one line or not. Previously it compared only the StartLineNumber of the first and last pipeline to be equal. Now the logic needs to be tweaked with an OR condition where also the EndLineNumber of the first and last pipeline is checked for equality.
Code was also made more readable.

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