Allow --enable-horizon-captive-core on pubnet, testnet #366

Job	Run time
arm64 / build-stellar-core	22s
arm64 / build-stellar-horizon	10m 18s
arm64 / build-stellar-friendbot	2m 56s
arm64 / build-stellar-soroban-rpc	1m 26s
amd64 / build-stellar-core	40s
amd64 / build-stellar-soroban-rpc	56s
amd64 / build-stellar-friendbot	59s
amd64 / build-stellar-horizon	2m 37s
amd64 / build	3m 47s
amd64 / test (testnet)	2m 31s
amd64 / test (pubnet)	1m 52s
amd64 / push-pr	1m 1s
amd64 / test (local)	1m 54s
amd64 / test (local, --enable-horizon-captive-core)	1m 44s
amd64 / push-release	0s
arm64 / build	8m 21s
arm64 / test (testnet)	13m 54s
arm64 / test (pubnet)	3m 54s
arm64 / test (local)	1m 50s
arm64 / push-pr	48s
arm64 / test (local, --enable-horizon-captive-core)	2m 46s
arm64 / push-release	0s
manifest / push	4s
complete	1s
	1h 4m 41s

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