confighttp: Ensure that auth errors use provided error handler (#12714) #29559

Job	Run time
govulncheck	1m 26s
setup-environment	37s
test-coverage	10m 56s
unittest-matrix (ubuntu-latest, ~1.24)	6m 20s
unittest-matrix (ubuntu-latest, ~1.23)	6m 17s
checks	2m 30s
cross-build-collector (aix, ppc64)	42s
lint	4m 42s
cross-build-collector (darwin, amd64)	46s
cross-build-collector (darwin, arm64)	48s
cross-build-collector (linux, 386)	50s
cross-build-collector (linux, amd64)	46s
cross-build-collector (linux, arm64)	54s
cross-build-collector (linux, ppc64le)	47s
cross-build-collector (linux, arm, 7)	41s
cross-build-collector (linux, s390x)	50s
cross-build-collector (windows, 386)	50s
cross-build-collector (windows, amd64)	56s
unittest	1s
	41m 39s

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