Tree: Fix handling of __focus_rect with various Select Modes

[BrotherShort]

Fix #107661

Under what conditions does the Tree update the meta data "__focus_rect"?

before #33286 :

Tree Select Mode	Selected Cells	Selected Row Selected Col Cell	Selected Row Other Cells
Single	√	√	√
Row	×	×	×
Multi	√	√	√

After #33286 :

Tree Select Mode	Selected Cells	Selected Row Selected Col Cell	Selected Row Other Cells
Single	√	×	×
Row	√	√	√
Multi	√	×	×

After #106286:

Tree Select Mode	Selected Cells	Selected Row Selected Col Cell	Selected Row Other Cells
Single	√	×	×
Row	√	√	√
Multi	√	√	√

Now:

Tree Select Mode	Selected Cells	Selected Row Selected Col Cell	Selected Row Other Cells
Single	√	×	×
Row	√	√	√
Multi	√	√	×

[KoBeWi]

The new condition handles all 3 select modes, so it should be much more reliable.
It does not bring back other regressions, and I checked some other Trees and they seem to work fine.

[akien-mga]

Thanks!