[3.15] gh-80504: Always show the full search path in IDLE Find in Files (GH-152740...

[3.15] gh-80504: Always show the full search path in IDLE Find in Files (GH-152740) (#152810)

gh-80504: Always show the full search path in IDLE Find in Files (GH-152740)

The "In files:" field of the Find in Files dialog now always contains a
full directory path, so the grep output shows which directory was searched.
(cherry picked from commit f21f338f1f88352d50362271a7f38c01745a65da)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>