testing: fix participation key expiration tests

[algonathan]

Summary

I've encountered an issue with the participation keys expiration test, which might cause flakiness.

Test Plan

I've managed to reproduce the same error as shown in
https://app.circleci.com/pipelines/github/algorand/go-algorand/5013/workflows/8c1f10b2-c827-4c0a-81a3-cfe18ec0c794/jobs/78980
By halting the secondary prior to the request of sclient for the round the rich client has.

[codecov-commenter]

Codecov Report

Merging #3621 (8a2c0d4) into master (212edb3) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3621      +/-   ##
==========================================
- Coverage   48.06%   48.03%   -0.03%     
==========================================
  Files         381      381              
  Lines       62080    62080              
==========================================
- Hits        29836    29819      -17     
- Misses      28822    28835      +13     
- Partials     3422     3426       +4     

Impacted Files	Coverage Δ
cmd/algoh/blockWatcher.go	77.77% <0.00%> (-3.18%)	⬇️
network/wsPeer.go	65.83% <0.00%> (-2.23%)	⬇️
crypto/merkletrie/trie.go	66.42% <0.00%> (-2.19%)	⬇️
crypto/merkletrie/node.go	91.62% <0.00%> (-1.87%)	⬇️
catchup/service.go	68.64% <0.00%> (-0.75%)	⬇️
network/wsNetwork.go	62.79% <0.00%> (-0.20%)	⬇️
ledger/acctupdates.go	66.41% <0.00%> (+0.94%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 212edb3...8a2c0d4. Read the comment docs.

[tsachiherman]

The changes here aren't bad, and probably would fix the failure; however, I do have few comments :

1. The test contains several calls to GetBalanceAndRound; most of them ignores the balance completely. Why don't we replace these with GetStatus() instead.
2. The added sClient.WaitForRound(richAccountLatestRound) makes sense, however, I would suggest replacing it with sClient.WaitForRound(lastValidRound+1) which aligns with the round number that the primary node was waited for.

[tsachiherman]

looks good to me. thanks for the changes.