Double finalization when using application interface in test programs

Nobody has claimed this yet.

### Describe the problem you're observing
When using the application interface, I got a unmount error at the end of execution.
it seems that the unifyfs_finalize() is called twice. See logs below.

### Describe how to reproduce the problem
With the -a flag, test_fini() will report a unmount error
`mpirun -n 1 write-static -n 1 -b 1048576 -f test -r -a --verbose`

### Include any warning or errors or releveant debugging data
```bash
DEBUG: finished stat
I/O pattern: N-to-1
2024-03-07T11:35:21 tid=884873 @ unifyfs_finalize() [unifyfs_api.c:295] syncing data
I/O block size: 1024.00 KiB
2024-03-07T11:35:21 tid=884873 @ unifyfs_finalize() [unifyfs_api.c:303] calling unmount
I/O request size: 1024.00 KiB
2024-03-07T11:35:21 tid=884873 @ invoke_client_unmount_rpc() [margo_client.c:391] invoking the unmount rpc function in client
Number of processes: 1
Each process wrote: 1.00 MiB
Total data written: 1.00 MiB
File create time: 0.005440 sec
Maximum write time: 0.001199 sec
Global write time: 0.001199 sec
Maximum sync time: 0.050524 sec
Global sync time: 0.050524 sec
File laminate time: 0.000000 sec
Full write time: 0.057638 sec
File stat time: 0.000421 sec
Aggregate write bandwidth: 834.028 MiB/s
Effective write bandwidth: 834.028 MiB/s

2024-03-07T11:39:39 tid=884943 @ get_page_size() [../../common/src/unifyfs_logio.c:83] returning page size 4096 B
2024-03-07T11:39:39 tid=884943 @ unifyfs_finalize() [unifyfs_api.c:295] syncing data
2024-03-07T11:39:39 tid=884943 @ unifyfs_finalize() [unifyfs_api.c:303] calling unmount
2024-03-07T11:39:39 tid=884943 @ unifyfs_finalize() [unifyfs_api.c:306] client unmount rpc failed
2024-03-07T11:39:39 tid=884943 @ get_page_size() [../../common/src/unifyfs_logio.c:83] returning page size 4096 B
UNIFYFS ERROR: unifyfs_unmount() failed with 'Failure'
```

Reproduce the issue with the provided mpirun command and inspect unifyfs_api.c around unifyfs_finalize(), along with the test_fini() path in write-static. Trace why the application interface reaches finalization twice; done means the command completes without a second unmount attempt or the reported unmount error.

Written by the indexing model from the issue text.