Improve performance of UseConsistentIndentation -> 35% speedup for formatter

[bergmeister]

PR Summary

Speedup is relative to the speed BEFORE my recent 2 PRs so that one sees the impact relative to those improvments (therefore the actual speedup relative to master would actually be higher). Speed is for a call of Invoke-Formatter with the default settings of the VS-Code extension.
Because the rule already loops through all tokens, there was a line that did a search through all tokens and the list of tokens can be quite long for big scripts.
First improvement would've been to create a list just consisting of pipeline tokens but even then I still saw some overhead just because it had to loop the whole list again. Therefore I optimized it further to just walk back on the current line, which is the only line of interest.
If we take this improvement and the previous 2 PRs together, then the formatter is nearly 3 times faster in total.

PR Checklist

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