kvs: add transaction stats #10120

Job	Run time
validate commits	13s
python linting	38s
Generate build matrix	7s
spelling	13s
bookworm - test-install	12m 37s
bookworm - 32 bit	13m 22s
noble - test-install	12m 43s
el9 - test-install	12m 10s
alpine - test-install	12m 21s
fedora40 - test-install	12m 7s
jammy - test-install	12m 37s
focal - py3.8	17m 22s
bookworm - gcc-12,content-s3,distcheck	19m 45s
fedora40 - clang-18	17m 16s
coverage	25m 23s
el8 - ascii	19m 35s
el8 - test-install	13m 53s
el8 - system,coverage	7m 24s
inception	21m 0s
flux-sched check	7m 2s
flux-pmix check	13m 9s
flux-pam check	4m 9s
flux-accounting check	5m 6s
macos build only	3m 24s
Generate docker manifest	1s
	4h 23m 37s

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