fix(buffers): bad sort_lastused result selection

[jamestrew]

Bad condition led to the selection being stuck at idx = 2 until only one result is left, despite idx = 1 result being a better match.

Neither sort_lastused or ignore_current_buffer should affect the position of the selection.
Former is used simply to sort the buffer list. The latter is used to filter out the current buffer.

closes #3262

[Conni2461]

This is actually a breaking change and was here for a reason. Sort last used matches the behavoir of fzf where we always select the last used buffer Index 2. Index 1 is always the current buffer.

[jamestrew]

Huh... That behavior doesn't really make sense to me 😅 but I can revert this and make a note of that in the docs instead of you prefer. I don't have a strong opinion on this.

[Conni2461]

we just need other behavior in the core picker. selection idx should be reset if default selection idx was set and you start typing. the idea behind having the previous buffer selected is that you can switch between current and previous buffer using telescope without navigating (you can do this with vim only ik, but ppl are ppl), this now is no longer possible.

see also #179