Remove initrd feature from the restricted kernel #10

Job	Run time
build_attest_all (buildconfigs/key_xor_test_app.sh)	2m 17s
build_attest_all (buildconfigs/oak_containers_kernel.sh)	11m 8s
build_attest_all (buildconfigs/oak_containers_orchestrator.sh)	6m 43s
build_attest_all (buildconfigs/oak_containers_stage1.sh)	3m 33s
build_attest_all (buildconfigs/oak_containers_syslogd.sh)	5m 40s
build_attest_all (buildconfigs/oak_containers_system_image.sh)	12m 9s
build_attest_all (buildconfigs/oak_echo_enclave_app.sh)	2m 22s
build_attest_all (buildconfigs/oak_echo_raw_enclave_app.sh)	11m 38s
build_attest_all (buildconfigs/oak_functions_enclave_app.sh)	2m 29s
build_attest_all (buildconfigs/oak_functions_insecure_enclave_app.sh)	2m 32s
build_attest_all (buildconfigs/oak_restricted_kernel_simple_io_init_rd_wrapper_bin.sh)	2m 49s
build_attest_all (buildconfigs/stage0_bin.sh)	2m 16s
build_attest_all (buildconfigs/oak_orchestrator.sh)	2m 23s
	1h 7m 59s

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