LaTeX template: Move \setstretch after front matter (#5378)

Ensures that `\maketitle`, `\tableofcontents`, and so forth are not affected by changes to line spacing. Closes #5179 by partially working around <https://github.com/reutenauer/polyglossia/issues/218>.

data/templates/default.latex

@@ -93,7 +93,6 @@ $else$
 $endif$
 $if(linestretch)$
 \usepackage{setspace}
-\setstretch{$linestretch$}
 $endif$
 \usepackage{amssymb,amsmath}
 \usepackage{ifxetex,ifluatex}
@@ -431,6 +430,9 @@ $endif$
 $if(lof)$
 \listoffigures
 $endif$
+$if(linestretch)$
+\setstretch{$linestretch$}
+$endif$
 $if(has-frontmatter)$
 \mainmatter
 $endif$