Bump test timeouts

A recent release of buildbuddy eliminated a timeout extension that
they had applied in the past. Now that they honor timeouts exactly,
we have had to adjust the timeout for many tests.

(cherry picked from commit 7d3d601)

Author: HoloRin

deps/rabbitmq_auth_backend_ldap/BUILD.bazel

@@ -88,7 +88,7 @@ suites = [
     rabbitmq_integration_suite(
         PACKAGE,
         name = "system_SUITE",
-        size = "small",
+        size = "medium",
         additional_srcs = [
             "test/rabbit_ldap_seed.erl",
         ],

deps/rabbitmq_stomp/BUILD.bazel

@@ -124,7 +124,7 @@ suites = [
     rabbitmq_integration_suite(
         PACKAGE,
         name = "proxy_protocol_SUITE",
-        size = "small",
+        size = "medium",
     ),
     rabbitmq_integration_suite(
         PACKAGE,