Re-enable local_cluster tests

[sakridge]

Problem

test_leader_failure_4, test_fail_entry_verification_leader, test_bad_blob_size_leader are disabled: #5347

Proposed Solution

Debug and re-enable.

[sakridge]

General failure mode is a hang with No next leader found. messages:
[2019-07-30T17:57:27.165505020Z ERROR solana::replay_stage] 8k8LuuWNChf7RyWNKaYpVSwdBaQFfAFpYJYnRAv46rb2 No next leader found

test_fail_entry_verification_leader:
https://buildkite.com/solana-labs/solana/builds/9835#bc72a001-55b9-46cb-b52d-b65f625c4b92

test_leader_failure_4:
https://buildkite.com/solana-labs/solana/builds/9820#9169745b-330c-406a-8035-ed8fdce9a3e7

[ParthDesai]

So, Ran above faulty tests 3-4 times isolated as well as with other local_cluster pkg tests.
But, I am not able to reproduce this error. Tests are passing successfully.

Sample output when running with other tests:

Parths-MacBook-Pro:solana parth$ cargo test --test local_cluster
    Finished dev [unoptimized + debuginfo] target(s) in 0.43s
     Running target/debug/deps/local_cluster-14a8d7a420000153

running 17 tests
test test_fake_blobs_broadcast_leader ... ignored
test test_forwarding ... ignored
test test_repairman_catchup ... ignored
test test_spend_and_verify_all_nodes_env_num_nodes ... ignored
test test_bad_blob_size_leader ... test test_bad_blob_size_leader has been running for over 60 seconds
test test_two_unbalanced_stakes ... test test_two_unbalanced_stakes has been running for over 60 seconds
test test_fullnode_exit_default_config_should_panic ... test test_fullnode_exit_default_config_should_panic has been running for over 60 seconds
test test_restart_node ... test test_restart_node has been running for over 60 seconds
test test_leader_failure_4 ... test test_leader_failure_4 has been running for over 60 seconds
test test_fullnode_exit_2 ... test test_fullnode_exit_2 has been running for over 60 seconds
test test_spend_and_verify_all_nodes_2 ... test test_spend_and_verify_all_nodes_2 has been running for over 60 seconds
test test_listener_startup ... test test_listener_startup has been running for over 60 seconds
test test_ledger_cleanup_service ... test test_ledger_cleanup_service has been running for over 60 seconds
test test_spend_and_verify_all_nodes_3 ... test test_spend_and_verify_all_nodes_3 has been running for over 60 seconds
test test_snapshots_restart_validity ... test test_snapshots_restart_validity has been running for over 60 seconds
test test_spend_and_verify_all_nodes_1 ... test test_spend_and_verify_all_nodes_1 has been running for over 60 seconds
test test_fail_entry_verification_leader ... test test_fail_entry_verification_leader has been running for over 60 seconds
test test_bad_blob_size_leader ... ok
test test_snapshots_restart_validity ... ok
[2019-08-23T15:21:34.856405000Z ERROR local_cluster] test_spend_and_verify_all_nodes_3
test test_spend_and_verify_all_nodes_3 ... ok
[2019-08-23T15:22:00.670234000Z ERROR local_cluster] test_spend_and_verify_all_nodes_2
test test_spend_and_verify_all_nodes_2 ... ok
[2019-08-23T15:22:17.026383000Z ERROR local_cluster] test_fullnode_exit_2
test test_fullnode_exit_2 ... ok
[2019-08-23T15:22:25.044676000Z ERROR local_cluster] test_restart_node
test test_restart_node ... ok
[2019-08-23T15:22:51.014612000Z ERROR local_cluster] test_two_unbalanced_stakes
test test_two_unbalanced_stakes ... ok
test test_fail_entry_verification_leader ... ok
[2019-08-23T15:25:26.540796000Z ERROR local_cluster] test_ledger_cleanup_service
test test_ledger_cleanup_service ... ok
[2019-08-23T15:26:52.635866000Z ERROR local_cluster] test_fullnode_exit_default_config_should_panic
test test_fullnode_exit_default_config_should_panic ... ok
[2019-08-23T15:27:01.956816000Z ERROR local_cluster] test_spend_and_verify_all_nodes_1
test test_spend_and_verify_all_nodes_1 ... ok
[2019-08-23T15:27:09.562203000Z ERROR local_cluster] test_leader_failure_4
test test_leader_failure_4 ... ok
test test_listener_startup ... ok

test result: ok. 13 passed; 0 failed; 4 ignored; 0 measured; 0 filtered out