kvs: add transaction stats #10141

Job	Run time
validate commits	9s
python linting	35s
Generate build matrix	10s
spelling	5s
bookworm - test-install	12m 55s
bookworm - 32 bit	14m 42s
noble - test-install	12m 44s
el9 - test-install	12m 59s
alpine - test-install	13m 3s
fedora40 - test-install	12m 27s
jammy - test-install	12m 14s
focal - py3.8	16m 37s
bookworm - gcc-12,content-s3,distcheck	19m 54s
fedora40 - clang-18	17m 2s
coverage	24m 42s
el8 - ascii	19m 51s
el8 - test-install	13m 5s
el8 - system,coverage	7m 4s
inception	21m 22s
flux-pmix check	12m 59s
flux-pam check	4m 20s
flux-accounting check	4m 34s
macos build only	3m 7s
flux-sched check	6m 41s
Generate docker manifest	1s
	4h 23m 22s

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