rptest: New license upgrade test

- Ensures licenses can be read/written by cluster between versions

(cherry picked from commit 1efea4c)

tests/rptest/tests/license_upgrade_test.py

@@ -108,3 +108,41 @@ def test_basic_upgrade(self):
 
         # Install license
         assert self.admin.put_license(license).status_code == 200
+
+
+class UpgradeMigratingLicenseVersion(RedpandaTest):
+    """
+    Verify that the cluster can interpret licenses between versions
+    """
+    def __init__(self, test_context):
+        super(UpgradeMigratingLicenseVersion,
+              self).__init__(test_context=test_context,
+                             num_brokers=3,
+                             si_settings=SISettings())
+        self.installer = self.redpanda._installer
+        self.admin = Admin(self.redpanda)
+
+    def setUp(self):
+        # 22.2.x is when license went live
+        self.installer.install(self.redpanda.nodes, (22, 2, 7))
+        super(UpgradeMigratingLicenseVersion, self).setUp()
+
+    @cluster(num_nodes=3, log_allow_list=RESTART_LOG_ALLOW_LIST)
+    def test_license_upgrade(self):
+        license = sample_license()
+        if license is None:
+            self.logger.info(
+                "Skipping test, REDPANDA_SAMPLE_LICENSE env var not found")
+            return
+
+        # Upload a license
+        self.admin.put_license(license)
+
+        # Update all nodes to newest version
+        self.installer.install(self.redpanda.nodes, RedpandaInstaller.HEAD)
+        self.redpanda.restart_nodes(self.redpanda.nodes)
+        _ = wait_for_num_versions(self.redpanda, 1)
+
+        # Attempt to read license written by older version
+        license = self.admin.get_license()
+        assert license is not None and license['loaded'] is True