[tests] fix the pytest tests executio on linux machine with SELinux

There is necessary to use "z" option when mounting files into the
container otherwise SELinux will not allow container to read the mounted
file.

Also, I've adjusted the UIDs used in the tests so that they are lower
than 65k because otherwise it's not possible to run these with a
root-less podman/docker.

tests/containers/base_image_test.py

@@ -21,7 +21,7 @@ class TestBaseImage:
     """Tests that are applicable for all images we have in this repository."""
 
     def test_oc_command_runs(self, image: str):
-        container = testcontainers.core.container.DockerContainer(image=image, user=123456, group_add=[0])
+        container = testcontainers.core.container.DockerContainer(image=image, user=23456, group_add=[0])
         container.with_command("/bin/sh -c 'sleep infinity'")
         try:
             container.start()
@@ -50,8 +50,8 @@ def test_oc_command_runs_fake_fips(self, image: str, subtests: pytest_subtests.S
             # tmpdir is by-default created with perms restricting access to user only
             tmp_crypto.chmod(0o777)
 
-            container = testcontainers.core.container.DockerContainer(image=image, user=654321, group_add=[0])
-            container.with_volume_mapping(str(tmp_crypto), "/proc/sys")
+            container = testcontainers.core.container.DockerContainer(image=image, user=54321, group_add=[0])
+            container.with_volume_mapping(str(tmp_crypto), "/proc/sys", mode="ro,z")
             container.with_command("/bin/sh -c 'sleep infinity'")
 
             try: