Increase timeout of cc_flags_supplier_test.

It timed out in https://buildkite.com/bazel/bazel-bazel/builds/11260#13690da0-cf9f-4597-af49-cd7af4656a59.

PiperOrigin-RevId: 292342082
diff --git a/src/test/shell/bazel/BUILD b/src/test/shell/bazel/BUILD
index 01fcbb9..2948698 100644
--- a/src/test/shell/bazel/BUILD
+++ b/src/test/shell/bazel/BUILD
@@ -1148,7 +1148,7 @@
 
 sh_test(
     name = "cc_flags_supplier_test",
-    size = "small",
+    size = "medium",
     srcs = ["cc_flags_supplier_test.sh"],
     data = [
         ":test-deps",