kvs: move "wait_version" API into "kvsroot" API #10272

Job	Run time
validate commits	10s
Generate build matrix	6s
python linting	36s
spelling	6s
bookworm - test-install	12m 19s
bookworm - 32 bit	13m 21s
noble - test-install	12m 43s
el9 - test-install	12m 23s
alpine - test-install	12m 58s
fedora40 - test-install	12m 11s
jammy - test-install	11m 59s
focal - py3.8	17m 26s
bookworm - gcc-12,content-s3,distcheck	20m 21s
fedora40 - clang-18	16m 45s
coverage	24m 56s
el8 - ascii	19m 52s
el8 - test-install	14m 4s
el8 - system,coverage	7m 16s
inception	21m 37s
flux-accounting check	5m 3s
flux-pam check	4m 31s
flux-sched check	6m 52s
flux-pmix check	13m 1s
macos build only	2m 56s
Generate docker manifest	1s
	4h 23m 33s

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