Remove usages of toBeTruthy/toBeFalsy in jest tests
## Context
We have a frontend testing guide to avoid usage of `toBeTruthy`/`toBeFalsy` https://docs.gitlab.com/ee/development/testing_guide/frontend_testing.html#avoid-using-tobetruthy-or-tobefalsy which can be enforced via eslint-plugin-jest. However, before enabling the rule we need to update all instances of this usage in `gitlab-ui`
## Solution
Please see strategies in [parent epic](https://gitlab.com/groups/gitlab-org/-/epics/8422#implementation-strategy)
issue