testsuite: ensure FLUX_HWLOC_XMLFILE works #2306

Job	Run time
spelling	7s
Generate build matrix	10s
validate commits	0s
python linting	51s
bookworm	24m 7s
bookworm - 32 bit	24m 36s
bookworm - gcc-12,content-s3,distcheck	24m 36s
bookworm - py3.11,clang-15	24m 34s
coverage	24m 34s
jammy - test-install	17m 5s
bookworm - test-install	18m 0s
focal - py3.8	24m 23s
el8	24m 35s
el8 - ascii	24m 36s
el8 - system,coverage	9m 44s
fedora34 - gcc-11.2,py3.9	24m 33s
fedora38 - gcc-13.1,py3.11	23m 23s
inception	24m 36s
flux-accounting check	5m 26s
flux-sched check	8m 22s
Generate docker manifest	1s
	5h 28m 19s

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