fix: whitelist.txt is superseded by allowlist.txt

[m90]

See: https://phabricator.wikimedia.org/T361551#9719481

This change was missed in #108 which updated to a version that does not support whitelist.txt anymore (albeit mentioned here) but instead expects allowlist.txt:

➜  queryservice git:(fr/allowlist) docker run --rm -it --entrypoint /bin/bash wikibase/wdqs:0.3.135-wmde.13                                                                                     wbaas-local
bash-4.4# cat runBlazegraph.sh | grep allowlist
ALLOWLIST=${ALLOWLIST:-"allowlist.txt"}
bash-4.4# cat runBlazegraph.sh | grep whitelist