deployment: add dummy_for_testing native config override layer

[nimrod-starkware]

The prepare-production-overlays CI job synths each prod overlay env-only
(-o hybrid. -o hybrid.common.dummy_for_testing), with no per-node leaf or
devops checkout. Under the native config path this errored on a missing
overrides.validator_id (and the consensus/mempool multiaddrs) because the
dummy_for_testing overlay had YAML but no native sequencer_config.jsonnet. Add
that layer (the folded nested translation of dummy_for_testing's YAMLs:
validator_id plus the #is_none multiaddrs as null) so env-only native synth
succeeds for mainnet, sepolia-alpha and sepolia-integration. Add the matching
*_layer_jsonnet_mirrors_combined_yaml regression test.

Co-Authored-By: Claude Opus 4.8 (1M context) noreply@anthropic.com

[nimrod-starkware]

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• deployment: drop redundant YAML sequencerConfig; source port-uniqueness from jsonnet #14659
• apollo_config,workspace: remove SerializeConfig trait and preset-dump machinery #14654
• apollo_config,apollo_node_config,apollo_config_manager: rework get_config_presentation off dump() #14653
• apollo_node_config,apollo_node: delete CONFIG_POINTERS data and pointer-remap from secrets bin #14652
• apollo_node_config,apollo_config_manager,apollo_integration_tests: retire preset config-generation path #14651
• apollo_node_config,apollo_deployments: assert cross-component equality for formerly-pointer-resolved fields #14650
• apollo_deployments: delete base app_configs and the preset-parity test machinery #14649
• apollo_node_config,apollo_node,deployment: source private_parameters from secrets schema, drop value config schema #14648
• apollo_deployments: retire dead preset/replacer generation machinery #14647
• deployment,apollo_deployments: drop config_format plumbing and retire preset config path #14646
• deployment: add native config layers for the testing overlays #14645
• deployment: add dummy_for_testing native config override layer #14632 👈 (View in Graphite)
• apollo_config: make native the sole config-load path #14631
• apollo_config,apollo_node_config: make config fields with custom deserializers serialize symmetrically #14630
• apollo_integration_tests,apollo_node_config: load integration-test node config via native format #14629
• deployment: add mainnet native config override layer #14628
• deployment: add sepolia-alpha native config override layer #14627
• apollo_deployments: test overrides list match #14626
• deployment,ci: add hybrid native override layers and their validation tests #14610
• deployment: add hybrid common native override layer + lockstep test #14655
• deployment: add native node-config builder and wire it into the ConfigMap #14609
• deployment: thread config_format from CLI to node container arg #14608
• apollo_deployments,deployment: set storage-reader-server ports as constants #14607
• apollo_node: add new CLI arg to parse config #14606
• apollo_deployments: check applicative config matches deployed app_configs #14489 : 2 other dependent PRs (#14480 , #14505 )
• apollo_deployments: assemble and deserialize node config from jsonnet #14487
• apollo_deployments: assemble full node config via build.libsonnet #14486
• apollo_deployments: distributed layout jsonnet test #14485
• apollo_deployments: consolidated layout jsonnet test #14484
• apollo_deployments: test hybrid layout for infra config #14483
• apollo_deployments: introduce hybrid layout for infra config #14482
• apollo_deployments: introduce jsonnet building blocks for infra config #14481
• apollo_deployments: jsonnet applicative config #14479
• main

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