fix(test): TestProvider is flaky

[arajasek]

This test sometimes fails, eg. on CI here: https://github.com/omni-network/omni/actions/runs/9764740221/job/26953786046

The failure rate is quite low, go test -run TestProvider -count 100000 only results in 10 or so failures. We need to:

• figure out whether this is a regression, or whether the test has always been flaky
• figure out why and fix it