[chore] Add AGENTS.md file #36780

Job	Run time
setup-environment	17s
test-coverage	7m 44s
govulncheck	3m 20s
unittest-matrix (ubuntu-latest, stable)	1m 25s
lint	14m 41s
unittest-matrix (ubuntu-latest, oldstable)	1m 23s
checks	2m 11s
cross-build-collector (aix, ppc64)	54s
cross-build-collector (linux, arm, 7)	56s
cross-build-collector (linux, riscv64)	1m 3s
cross-build-collector (linux, amd64)	1m 3s
cross-build-collector (linux, ppc64le)	57s
cross-build-collector (windows, 386)	59s
cross-build-collector (darwin, arm64)	54s
cross-build-collector (darwin, amd64)	56s
cross-build-collector (linux, 386)	1m 4s
cross-build-collector (linux, s390x)	53s
cross-build-collector (windows, arm64)	53s
cross-build-collector (linux, arm64)	1m 0s
cross-build-collector (windows, amd64)	55s
unittest	3s
	43m 31s

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