Wrong block time for integration tests. 24 sec instead of expected 12 sec

[RustNinja]

The block time for integration tests is 24 sec.
The issue related to missing Bob node for parachains.
the settings for collator sections is in testnet_geneisis spec rs

Need to remove to fix block time.

(
   get_account_id_from_seed::<sr25519::Public>("Bob"),
   get_collator_keys_from_seed("Bob"),
),

[josietyleung]

closing as merged