chore: deprecate timeout_commit and timeout_propose config

[rootulp]

Closes #1550

Testing

In celestia-app I replaced celestia-core with this repo. Then created a new config file and observed:

# How long we wait for a proposal block before prevoting nil
# Deprecated: timeout_commit is overridden by the state machine in app version >= 3.
# Therefore, the value set in this config will be ignored.
timeout_propose = "3.5s"

# How long we wait after committing a block, before starting on the new
# height (this gives us a chance to receive some more precommits, even
# though we already have +2/3).
# Deprecated: timeout_commit is overridden by the state machine in app version >= 3.
# Therefore, the value set in this config will be ignored.
timeout_commit = "4.2s"