[antlir2][apt] bring back tests

Summary:
These were deleted in D110186663 because the old snapshot aged out, but it's
fixed now.

Test Plan:
```
❯ buck2 test fbcode//antlir/antlir2/features/apt/...
Buck UI: https://www.internalfb.com/buck2/253fa931-398c-43f5-bab5-9311ccf26a46
Tests finished: Pass 6. Fail 0. Timeout 0. Fatal 0. Skip 0. Omit 0. Infra Failure 0. Build failure 0
```
https://www.internalfb.com/intern/testinfra/testrun/9570149399046508

Reviewed By: justintrudell

Differential Revision: D116816199

fbshipit-source-id: 504cdb0ccd02b2b15b70b1f1502b4b07031c7fa4

Author: vmagro

antlir/antlir2/features/apt/tests/BUCK

@@ -0,0 +1,51 @@
+load("//antlir/antlir2/bzl/feature:defs.bzl", "feature")
+load("//antlir/antlir2/bzl/image:defs.bzl", "image")
+load("//antlir/antlir2/testing:image_debs_test.bzl", "image_test_deb_names")
+
+oncall("antlir")
+
+image.layer(
+    name = "bash-installed",
+    default_os = "debian-trixie",
+    features = [
+        feature.apt_install(
+            packages = [
+                "bash",
+                "dash",
+                "dpkg",
+            ]
+        ),
+    ],
+)
+
+image_test_deb_names(
+    name = "test-bash-installed",
+    layer = ":bash-installed",
+    names = [
+        "bash",
+        "dash",
+        "dpkg",
+    ],
+)
+
+image.layer(
+    name = "bash-removed",
+    default_os = "debian-trixie",
+    features = [
+        feature.apt_remove(
+            packages = [
+                "bash",
+            ]
+        ),
+    ],
+    parent_layer = ":bash-installed",
+)
+
+image_test_deb_names(
+    name = "test-bash-removed",
+    layer = ":bash-removed",
+    names = [
+        "bash",
+    ],
+    not_installed = True,
+)