gnu: texlive-xmltex: Rely on build system to create formats.
* gnu/packages/tex.scm (texlive-xmltex)[arguments]: Use #:CREATE-FORMATS.
Remove useless phase.
[propagated-inputs]: Remove call to TEXLIVE-UPDMAP.CFG. Remove
TEXLIVE-AMSFONTS, TEXLIVE-COURIER, TEXLIVE-DEHYPH, TEXLIVE-HELVETIC,
TEXLIVE-HYPERREF, TEXLIVE-HYPHEN-BASE, TEXLIVE-HYPH-UTF8, TEXLIVE-STMARYRD,
TEXLIVE-SYMBOL, TEXLIVE-TIMES, TEXLIVE-TIPA, TEXLIVE-WASY, TEXLIVE-ZAPFDING.
Add TEXLIVE-HYPHEN-COMPLETE, TEXLIVE-LATEX, TEXLIVE-LATEXCONFIG,
TEXLIVE-PDFTEX, TEXLIVE-TEX, TEXLIVE-UNICODE-DATA.