fix(bft): potential deadlock in the consensus ticker on close

[gfanton]

This PR addresses a potential deadlock issue that can occur if ScheduleTimeout is used after the timeoutTicker service has been stopped. This problem has been observed in some CI jobs when stopping the node: https://github.com/gnolang/gno/actions/runs/9301771431/attempts/1 (thanks @thehowl).

The stacktrace indicates that timeoutTicker has likely been closed before ConsensusState, and ConsensusState is getting stuck while calling ScheduleTimeout because the tickChan will never be read.

The proposed solution is to simply ignore any scheduled timeouts if the timeoutTicker service has been closed.

I've extracted the relevant part of the stacktrace:

• The first stack shows the ConsensusReactor waiting for ConsensusState on stop.
• The second stack shows ConsensusState waiting to ScheduleTimeout on the timeoutTicker.

coverage: 53.8% of statements
panic: test timed out after 30m0s
running tests:
	TestTestdata (30m0s)
	TestTestdata/gnoland (29m54s)

---

goroutine 11039 [chan receive, 29 minutes]:
github.com/gnolang/gno/tm2/pkg/bft/consensus.(*ConsensusState).Wait(...)
	/home/runner/work/gno/gno/tm2/pkg/bft/consensus/state.go:376
github.com/gnolang/gno/tm2/pkg/bft/consensus.(*ConsensusReactor).OnStop(0xc000176a00)
	/home/runner/work/gno/gno/tm2/pkg/bft/consensus/reactor.go:92 +0x75
github.com/gnolang/gno/tm2/pkg/service.(*BaseService).Stop(0xc000176a00)
	/home/runner/work/gno/gno/tm2/pkg/service/service.go:168 +0x22e
github.com/gnolang/gno/tm2/pkg/p2p.(*Switch).OnStop(0xc000396600)

---

goroutine 15586 [chan send, 29 minutes]:
github.com/gnolang/gno/tm2/pkg/bft/consensus.(*timeoutTicker).ScheduleTimeout(0x1d4e957d?, {0x5ed0bdb, 0x7, 0x0, 0x1})
	/home/runner/work/gno/gno/tm2/pkg/bft/consensus/ticker.go:71 +0x30
github.com/gnolang/gno/tm2/pkg/bft/consensus.(*ConsensusState).scheduleTimeout(...)
	/home/runner/work/gno/gno/tm2/pkg/bft/consensus/state.go:472
github.com/gnolang/gno/tm2/pkg/bft/consensus.(*ConsensusState).scheduleRound0(0xc000ff7508, 0xc000ff7598)
	/home/runner/work/gno/gno/tm2/pkg/bft/consensus/state.go:467 +0x8b
...
github.com/gnolang/gno/tm2/pkg/bft/consensus.(*ConsensusState).tryAddVote(0xc000ff7508, 0x41bdda?, {0x0?, 0x7f11457181a8?})
	/home/runner/work/gno/gno/tm2/pkg/bft/consensus/state.go:1518 +0x2f
github.com/gnolang/gno/tm2/pkg/bft/consensus.(*ConsensusState).handleMsg(0xc000ff7508, {{0x12fc4c0, 0xc000fe59f0}, {0x0, 0x0}})
	/home/runner/work/gno/gno/tm2/pkg/bft/consensus/state.go:696 +0xf8
github.com/gnolang/gno/tm2/pkg/bft/consensus.(*ConsensusState).receiveRoutine(0xc000ff7508, 0x0)
	/home/runner/work/gno/gno/tm2/pkg/bft/consensus/state.go:655 +0x452
created by github.com/gnolang/gno/tm2/pkg/bft/consensus.(*ConsensusState).OnStart in goroutine 11039
	/home/runner/work/gno/gno/tm2/pkg/bft/consensus/state.go:349 +0x4ef

---

Contributors' checklist...

• Added new tests, or not needed, or not feasible
• Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• Updated the official documentation or not needed
• No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• Added references to related issues and PRs
• Provided any useful hints for running manual tests
• Added new benchmarks to generated graphs, if any. More info here.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 54.63%. Comparing base (edb321f) to head (3f24aaf).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2264      +/-   ##
==========================================
- Coverage   54.64%   54.63%   -0.02%     
==========================================
  Files         578      578              
  Lines       77870    77873       +3     
==========================================
- Hits        42551    42543       -8     
- Misses      32149    32158       +9     
- Partials     3170     3172       +2     

Flag	Coverage Δ
tm2	54.41% <100.00%> (-0.09%)	⬇️

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