Investigate intermittent test failure in write_buffer test

When running tests locally ran into the following test failure,

```
--- STDERR: influxdb3_write write_buffer::tests::last_cache_create_and_delete_is_durable ---
thread 'write_buffer::tests::last_cache_create_and_delete_is_durable' panicked at influxdb3_write/src/write_buffer/mod.rs:850:10:
called `Result::unwrap()` on an `Err` value: WalError(ObjectStoreError(NotFound { path: "test_host/wal/00000000004.wal", source: NoDataInMemory { path: "test_host/wal/00000000004.wal" } }))
stack backtrace:
0: rust_begin_unwind
at /rustc/051478957371ee0084a7c0913941d2a8c4757bb9/library/std/src/panicking.rs:652:5
1: core::panicking::panic_fmt
at /rustc/051478957371ee0084a7c0913941d2a8c4757bb9/library/core/src/panicking.rs:72:14
2: core::result::unwrap_failed
at /rustc/051478957371ee0084a7c0913941d2a8c4757bb9/library/core/src/result.rs:1679:5
3: core::result::Result::unwrap
at /rustc/051478957371ee0084a7c0913941d2a8c4757bb9/library/core/src/result.rs:1102:23
4: influxdb3_write::write_buffer::tests::last_cache_create_and_delete_is_durable::{{closure}}
at ./src/write_buffer/mod.rs:835:20
5: as core::future::future::Future>::poll
at /rustc/051478957371ee0084a7c0913941d2a8c4757bb9/library/core/src/future/future.rs:123:9
6: as core::future::future::Future>::poll
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tracing-0.1.40/src/instrument.rs:321:9
7: as core::future::future::Future>::poll
at /rustc/051478957371ee0084a7c0913941d2a8c4757bb9/library/core/src/future/future.rs:123:9
8: tokio::runtime::scheduler::current_thread::CoreGuard::block_on::{{closure}}::{{closure}}::{{closure}}
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/scheduler/current_thread/mod.rs:696:57
9: tokio::runtime::coop::with_budget
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/coop.rs:107:5
10: tokio::runtime::coop::budget
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/coop.rs:73:5
11: tokio::runtime::scheduler::current_thread::CoreGuard::block_on::{{closure}}::{{closure}}
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/scheduler/current_thread/mod.rs:696:25
12: tokio::runtime::scheduler::current_thread::Context::enter
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/scheduler/current_thread/mod.rs:423:19
13: tokio::runtime::scheduler::current_thread::CoreGuard::block_on::{{closure}}
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/scheduler/current_thread/mod.rs:695:36
14: tokio::runtime::scheduler::current_thread::CoreGuard::enter::{{closure}}
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/scheduler/current_thread/mod.rs:774:68
15: tokio::runtime::context::scoped::Scoped::set
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/context/scoped.rs:40:9
16: tokio::runtime::context::set_scheduler::{{closure}}
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/context.rs:180:26
17: std::thread::local::LocalKey::try_with
at /rustc/051478957371ee0084a7c0913941d2a8c4757bb9/library/std/src/thread/local.rs:283:12
18: std::thread::local::LocalKey::with
at /rustc/051478957371ee0084a7c0913941d2a8c4757bb9/library/std/src/thread/local.rs:260:9
19: tokio::runtime::context::set_scheduler
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/context.rs:180:9
20: tokio::runtime::scheduler::current_thread::CoreGuard::enter
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/scheduler/current_thread/mod.rs:774:27
21: tokio::runtime::scheduler::current_thread::CoreGuard::block_on
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/scheduler/current_thread/mod.rs:683:19
22: tokio::runtime::scheduler::current_thread::CurrentThread::block_on::{{closure}}
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/scheduler/current_thread/mod.rs:191:28
23: tokio::runtime::context::runtime::enter_runtime
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/context/runtime.rs:65:16
24: tokio::runtime::scheduler::current_thread::CurrentThread::block_on
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/scheduler/current_thread/mod.rs:179:9
25: tokio::runtime::runtime::Runtime::block_on_inner
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/runtime.rs:361:47
26: tokio::runtime::runtime::Runtime::block_on
at /home/praveen/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.40.0/src/runtime/runtime.rs:335:13
27: influxdb3_write::write_buffer::tests::last_cache_create_and_delete_is_durable
at ./src/write_buffer/mod.rs:852:9
28: influxdb3_write::write_buffer::tests::last_cache_create_and_delete_is_durable::{{closure}}
at ./src/write_buffer/mod.rs:704:55
29: core::ops::function::FnOnce::call_once
at /rustc/051478957371ee0084a7c0913941d2a8c4757bb9/library/core/src/ops/function.rs:250:5
30: core::ops::function::FnOnce::call_once
at /rustc/051478957371ee0084a7c0913941d2a8c4757bb9/library/core/src/ops/function.rs:250:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

```

The same test has failed in CI as well,
https://app.circleci.com/pipelines/github/influxdata/influxdb/41703/workflows/da14ee4d-e712-42c2-a5b9-f5cba67c1af1/jobs/389885

Start with influxdb3_write/src/write_buffer/mod.rs and the write_buffer::tests::last_cache_create_and_delete_is_durable test, which fails at the reported unwrap with a missing WAL object. Run the test locally and compare its behavior with the linked CircleCI failure; done means identifying and addressing the intermittent failure so the test passes reliably.

Written by the indexing model from the issue text.