Fix label sanitization for strings that end in a period (#8151)

Summary:
(or have a period at the end  when they are truncated)

Test Plan: BK, verify new test was failing before

python_modules/libraries/dagster-k8s/dagster_k8s/utils.py

@@ -13,7 +13,7 @@ def sanitize_k8s_label(label_name: str):
     # Truncate too long label values to fit into 63-characters limit and avoid invalid characters.
     # https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set
     label_name = label_name[:63]
-    return re.sub(r"[^a-zA-Z0-9\-_\.]", "-", label_name).strip("-").strip("_")
+    return re.sub(r"[^a-zA-Z0-9\-_\.]", "-", label_name).strip("-").strip("_").strip(".")
 
 
 def retrieve_pod_logs(pod_name, namespace):

python_modules/libraries/dagster-k8s/dagster_k8s_tests/unit_tests/test_job.py

@@ -1,3 +1,5 @@
+import re
+
 import pytest
 from dagster_k8s import DagsterK8sJobConfig, construct_dagster_k8s_job
 from dagster_k8s.job import (
@@ -681,3 +683,30 @@ def test_sanitize_labels():
 
     assert job["metadata"]["labels"]["dagster/op"] == "get_f-o.o-bar-0"
     assert job["metadata"]["labels"]["my_label"] == "WhatsUP"
+
+
+# Taken from the k8s error message when a label is invalid
+K8s_LABEL_REGEX = r"(([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9])?"
+
+
+def test_sanitize_labels_regex():
+
+    assert re.fullmatch(K8s_LABEL_REGEX, sanitize_k8s_label("normal-string"))
+
+    assert not re.fullmatch(
+        K8s_LABEL_REGEX,
+        "string-with-period.",
+    )
+
+    assert re.fullmatch(
+        K8s_LABEL_REGEX,
+        sanitize_k8s_label("string-with-period."),
+    )
+
+    # string that happens to end with a period after being truncated to 63 characters
+    assert re.fullmatch(
+        K8s_LABEL_REGEX,
+        sanitize_k8s_label(
+            "data_pipe_graph_abcdefghi_jklmn.raw_data_graph_abcdefghi_jklmn.opqrstuvwxyz"
+        ),
+    )