fix(lifecycle): restore #[serial] on 2 tests that read env vars without temp_env

eval_inner_expires_latest_object_after_days_due and
eval_inner_does_not_panic_on_many_equal_due_events call eval_inner()
which reads ENV_ILM_PROCESS_TIME via std::env::var(). Without #[serial]
they race with other tests that set these vars via temp_env.

crates/lifecycle/Cargo.toml

@@ -69,6 +69,7 @@ uuid = { workspace = true, features = ["v4", "serde", "fast-rng", "macro-diagnos
 [dev-dependencies]
 metrics-util = { workspace = true, features = ["debugging"] }
 proptest = "1"
+serial_test = { workspace = true }
 temp-env.workspace = true
 tokio = { workspace = true, features = ["macros", "fs", "rt-multi-thread"] }