refactor: make shellcheck fixes

Refs: PT-1952

Author: charn

docker-entrypoint.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 set -e
 
-if [ -z "$SKIP_DATABASE_CHECK" -o "$SKIP_DATABASE_CHECK" = "0" ]; then
+if [ -z "$SKIP_DATABASE_CHECK" ] || [ "$SKIP_DATABASE_CHECK" = "0" ]; then
   until nc -z -v -w30 "$DATABASE_HOST" 5432
   do
     echo "Waiting for postgres database connection..."
@@ -18,7 +18,7 @@ if [[ "$APPLY_MIGRATIONS" = "1" ]]; then
 fi
 
 # Start server
-if [[ ! -z "$@" ]]; then
+if [[ -n "$*" ]]; then
     "$@"
 elif [[ "$DEV_SERVER" = "1" ]]; then
     python ./manage.py runserver 0.0.0.0:8081