zombienet_tests: Fix genesis error in 0006-parachains-max-tranche0.toml (#2191)

There was a race in merging between
https://github.com/paritytech/polkadot-sdk/pull/1256 and
https://github.com/paritytech/polkadot-sdk/pull/1178, so this newly
added tests wasn't updated with the new path for the configuration, so
fix that.

Signed-off-by: Alexandru Gheorghe <[email protected]>