Ensure that babel is loaded also with pdflatex.

This fixes a regression in #7604, which modernized
babel usage but omitted to load babel for pdflatex,
with the result that even simple documents could no
longer be produced.

Closes #7627.

data/templates/default.latex

@@ -363,11 +363,10 @@ $if(csl-refs)$
 \newcommand{\CSLIndent}[1]{\hspace{\cslhangindent}#1}
 $endif$
 $if(lang)$
-\ifXeTeX
-\usepackage[bidi=default]{babel}
-\fi
 \ifLuaTeX
 \usepackage[bidi=basic]{babel}
+\else
+\usepackage[bidi=default]{babel}
 \fi
 \babelprovide[main,import]{$babel-lang$}
 $for(babel-otherlangs)$

test/writers-lang-and-dir.latex

@@ -44,11 +44,10 @@
 \providecommand{\tightlist}{%
   \setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}
 \setcounter{secnumdepth}{-\maxdimen} % remove section numbering
-\ifXeTeX
-\usepackage[bidi=default]{babel}
-\fi
 \ifLuaTeX
 \usepackage[bidi=basic]{babel}
+\else
+\usepackage[bidi=default]{babel}
 \fi
 \babelprovide[main,import]{english}
 \babelprovide[import]{ngerman}