Flaky test: test/e2e-go/upgrades TestRekeyUpgrade

## Description
Travis Test Errors Reference Spreadsheet for details on cases where this test has failed: https://docs.google.com/spreadsheets/d/1apjaNvZodnTSIdZaQlpMaqf0nzbKgSYdIWHqvmINHS8/edit#gid=0

### Example Failure
Time: Wed 7/21/2021
Build: https://app.travis-ci.com/github/algorand/go-algorand/jobs/525817897#L2859
Travis Test: External ARM64 Integration Test
Package: test/e2e-go/upgrades
Test: TestRekeyUpgrade
```
algod(6371) : Success!
algod(6371) : ⇨ http server started on 127.0.0.1:35829
algod(6371) : Node running and accepting RPC requests over HTTP on port 127.0.0.1:35829. Press Ctrl-C to exit
time="2021-07-21T02:20:13.749952 +0000" level=warning msg="dbatomic: tx surpassed expected deadline by 7.334518929s" callee=github.com/[secure]/go-[secure]/data/account.RestoreParticipation.func1 caller="/home/ubuntu/go/src/github.com/[secure]/go-[secure]/data/account/account.go:145" file=dbutil.go function="github.com/[secure]/go-[secure]/util/db.(*Accessor).atomic" line=344 readonly=false
fixture.go:105:
Error Trace: rekey_support_test.go:84
Error: An error is expected but got nil.
Test: TestRekeyUpgrade
algod(6371) : Exiting on terminated
algod(6360) : Exiting on terminated
DONE 121 tests, 2 skipped, 1 failure in 3493.123s
Makefile:247: recipe for target 'integration' failed
make: *** [integration] Error 1
The command "/home/ubuntu/go/src/github.com/[secure]/go-[secure]/scripts/travis/test.sh" failed. Retrying, 2 of 3.
```