kvs: add transaction stats #10118

Job	Run time
validate commits	9s
spelling	7s
Generate build matrix	8s
python linting	34s
bookworm - test-install	1m 22s
bookworm - 32 bit	1m 22s
noble - test-install	1s
el9 - test-install	1s
alpine - test-install	1m 22s
fedora40 - test-install	1s
jammy - test-install	1s
focal - py3.8	1m 21s
bookworm - gcc-12,content-s3,distcheck	1m 22s
fedora40 - clang-18	1s
coverage	1m 21s
el8 - ascii	1m 19s
el8 - test-install	1m 22s
el8 - system,coverage	1m 21s
inception	1s
macos build only	55s
flux-pmix check	1s
flux-accounting check	1s
flux-pam check	1s
flux-sched check	1s
Generate docker manifest	1s
	14m 16s

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