fix: Properly shutdown quickwit-serve when subcomponents panic or otherwise error.

[philip-wernersbach]

Description

Before this change, the if let Err block silently swallows the error and logs it. The code continues on to the shutdown_handle.await call. In the case where the tokio::try_join! returns an error (such as when any of the three components for the three JoinHandle arguments panic), the shutdown_handle is not guaranteed to have completed, so the program sits there waiting for a SIGTERM, even though some components aren’t running.

Context

We are seeing the following chitchat panic in prod, in our metastore pods. After the panic message is printed, the ERROR quickwit_serve: server failed: Chitchat server panicked message is printed, and the program waits to for a SIGTERM. No further log messages are printed until the SIGTERM occurs. Meanwhile, our quickwit-indexer pods do not work, because the chitchat with metastore is broken.

thread 'main_runtime_thread' (17) panicked at /usr/local/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/chitchat-0.10.0/src/state.rs:605:17:
assertion failed: monotonic_property_after >= monotonic_property_before
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
2026-03-06T13:59:04.262Z ERROR quickwit_serve: server failed: Chitchat server panicked

How was this PR tested?

Built a custom Docker image with this fix, tested in prod:

1. Happy path: SIGTERM still shuts down pods:

2026-03-10T14:45:27.543Z  INFO quickwit_cli::service: SIGTERM received
2026-03-10T14:45:27.543Z  INFO quickwit_serve::rest: REST server shutdown signal received
2026-03-10T14:45:27.543Z  INFO quickwit_serve::rest: gracefully shutdown
2026-03-10T14:45:27.545Z  INFO quickwit_serve: waiting for services to shutdown
2026-03-10T14:45:28.546Z  INFO quickwit_cli::service: quickwit successfully terminated

2. Error path: chitchat panic causes pod to shut down:

thread 'main_runtime_thread' (8) panicked at /usr/local/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/chitchat-0.10.0/src/state.rs:605:17:
assertion failed: monotonic_property_after >= monotonic_property_before
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
2026-03-10T02:54:34.891Z ERROR quickwit_serve: server failed: Chitchat server panicked
2026-03-10T02:54:34.891Z  INFO quickwit_serve: waiting for services to shutdown
2026-03-10T02:54:34.891Z  INFO quickwit_serve::rest: REST server shutdown signal received
2026-03-10T02:54:34.891Z  INFO quickwit_serve::rest: gracefully shutdown
2026-03-10T02:54:35.892Z  INFO quickwit_cli::service: #Quickwit successfully terminated

[philip-wernersbach]

Added results from a test in prod.