[SUPERSEDED] Undo patch of double-block apply

[som-snytt]

If f{}{} is candidate for rewrite, unpatch it.

We don't know exact spans, so just check endpoints to remove.

Fixes #21382

[som-snytt]

Not a satisfying solution, but has the virtue of discretion (of being discrete).

It would be more natural to check lastToken against colonEOLPredecessors and turn off canRewrite. I expected to have to scan backward in text for previous token, and set a variable like possibleColonOffset to turn off the rewrite non-contextually.

[bracevac]

@som-snytt do you plan to work on this or should I take it from here?

[som-snytt]

@bracevac I had no immediate plan. Feel free to either use it or lose it!

[som-snytt]

superseded by #21982