bug#56815: 29.0.50; Isearch lazy-highlight highlights too much when truncate-lines is in effect

[Juri Linkov]

> You can now use the new long-line-optimizations-p predicate for that.
> Although from your description above, perhaps Isearch should behave
> like that in a buffer with line-truncation regardless of the long
> lines.

This means using the same condition like in 'line-move'?

                  (and
                   (or truncate-lines
                       (and (integerp truncate-partial-width-windows)
                            (< (window-total-width)
                               truncate-partial-width-windows))
                       (and truncate-partial-width-windows
                            (not (integerp truncate-partial-width-windows))
                            (not (window-full-width-p))))
                   ;; ...or if lines are truncated, this buffer
                   ;; doesn't have very long lines.
                   (long-line-optimizations-p))

I suggest to leave 'long-line-optimizations-p' at the end because
in such cases when 'lazy-highlight-cleanup' is customized to nil
the users might want to leave highlighting on truncated lines
after exiting Isearch to see matches when scrolling horizontally
(when lines are not long).