Flakiness in Thanos e2e test causing build failures

[shayyxi]

Thanos, Prometheus and Golang version used:

Object Storage Provider:

What happened:
Thanos end-to-end tests (4, 0) is flaky and fails sometimes during build process. The test is flaky and causes unnecessary build failures.

What you expected to happen:
The test should not fail without a solid reason.

How to reproduce it (as minimally and precisely as possible):
It is hard to reproduce but it can be observed in few PRs.

Full logs to relevant components:

Anything else we need to know:
I have mentioned this issue in thanos-dev slack channel and I would be working on it.