DAOS-16585 tests: Fix NLT handling of __fxstat detection #6780

Job	Run time
Build DAOS (alma.8)	40m 7s
Build DAOS (ARM64) (ubuntu, clang)	1s
Create Docker images (ubuntu)	8m 45s
Build DAOS (alma.9)	38m 30s
Build DAOS (ARM64) (alma.8, clang)	1s
Create Docker images (rocky)	9m 34s
Build DAOS (rocky.8)	38m 58s
Build DAOS (ARM64) (leap.15, clang)	1s
Create Docker images (fedora)	9m 33s
Build DAOS (ubuntu)	37m 1s
Create Docker images (leap.15)	12m 44s
Run DAOS/NLT tests (ubuntu)	24m 25s
Build DAOS in image (ubuntu, clang)	22m 28s
Build DAOS in image (ubuntu, gcc)	23m 6s
Build DAOS in image (rocky, clang)	24m 30s
Build DAOS in image (rocky, gcc)	25m 35s
Build DAOS in image (fedora, clang)	23m 34s
Build DAOS in image (fedora, gcc)	25m 8s
Build DAOS in image (leap.15, clang)	24m 18s
Build DAOS in image (leap.15, gcc)	24m 46s
	6h 53m 5s

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