Revert "Enclose tree report image path and file name in braces"

Fixes #12437 by reverting commit 75921ceaf4 due to
reports of regression where processing of the generated TeX file fails due to
bad path specificiation for image files.

Change was introduced in bug fix for #10495.

Bugs #12437 and #12697 reported the regression and confirmed that reverting the
change fixes the regression.

gramps/gen/plug/docgen/treedoc.py

@@ -460,8 +460,7 @@ class TreeDocBase(BaseDoc, TreeDoc):
             if os.path.isfile(path):
                 if win():
                     path = path.replace('\\', '/')
-                self.write(level+1, 'image = {{%s}%s},\n' %
-                           os.path.splitext(path))
+                self.write(level+1, 'image = {%s},\n' % path)
                 break # first image only
         self.write(level, '}\n')