update run-unit-tests.sh to work with unittest, ensure env vars are correct

bin/run-unit-tests.sh

@@ -1,5 +1,13 @@
 #!/bin/bash
 
+# unset all environment variables which have been set in .env file
+unset $(sed -n -e 's/^\s*\([^#][^=]*\)=.*/\1/p' .env)
+
+# set environment variables from .env-test file
+set -o allexport
+source .env-test
+set +o allexport
+
 set -ex
 
 # wait on database in DATABASE_URL to be ready
@@ -10,4 +18,4 @@ urlwait http://elasticsearch7:9200 60
 
 ./manage.py es7_init --migrate-writes --migrate-reads
 
-./manage.py test --noinput --nologcapture -a '!search_tests'
+./manage.py test --noinput