tools/docker: Fixup test config file name

Apparently commit

492d42dddb63 ("target: tests: Address review comments on PR#667")

erroneously renamed target_configs.yaml to target_configs.yml.
Rename it to test_config.yml.

Also address 2 Docker warnings related to environment variables while we
are here.

Signed-off-by: Metin Kaya <metin.kaya@arm.com>

tools/docker/Dockerfile

@@ -24,9 +24,9 @@
 
 FROM ubuntu:22.04
 
-ENV DEBIAN_FRONTEND noninteractive
+ENV DEBIAN_FRONTEND=noninteractive
 
-ENV DEVLIB_REF master
+ENV DEVLIB_REF=master
 
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \

tools/docker/run_tests.sh

@@ -37,5 +37,5 @@ echo "Waiting 30 seconds for Android virtual devices to finish boot up..."
 sleep 30
 
 cd /devlib
-cp -f tools/docker/target_configs.yaml tests/
+cp -f tools/docker/test_config.yml tests/
 python3 -m pytest --log-cli-level DEBUG ./tests/test_target.py