feat: add DCO signoffs to remaining test files

Add DCO signoffs to 00, 01, 04, and 08 test files to complete
DCO compliance for all files in the PR.

Signed-off-by: Yossi Ovadia <[email protected]>

Author: yossiovadia

e2e-tests/00-client-request-test.py

@@ -4,6 +4,8 @@
 
 This test validates that the Envoy proxy is running and accepting requests,
 and that basic request formatting works correctly.
+
+Signed-off-by: Yossi Ovadia <[email protected]>
 """
 
 import json

e2e-tests/01-envoy-extproc-test.py

@@ -5,6 +5,8 @@
 This test verifies that Envoy is correctly forwarding requests to the ExtProc,
 and that the ExtProc is responding with appropriate routing decisions.
 These tests use custom headers to trace request processing.
+
+Signed-off-by: Yossi Ovadia <[email protected]>
 """
 
 import json

e2e-tests/04-cache-test.py

@@ -4,6 +4,8 @@
 
 This test validates the semantic cache functionality by sending similar
 queries and checking if cache hits occur as expected.
+
+Signed-off-by: Yossi Ovadia <[email protected]>
 """
 
 import json

e2e-tests/08-metrics-test.py

@@ -4,6 +4,8 @@
 
 This test validates that all metrics endpoints are working correctly and
 that the router is properly recording performance and operational metrics.
+
+Signed-off-by: Yossi Ovadia <[email protected]>
 """
 
 import json