Gitlab: Don't mix logics

We are doing it this way all over the PKGBUILD:

    _etcdir=/foo/bar
    package() {
      mv my_file "${pkgdir}/{_etcdir}"
    }

rather than this way:

    _etcdir="${pkgdir}/foo/bar"
    package() {
      mv my_file "${_etcdir}"
    }

I don't care which way we choose but let's be consistent.