Fix flaky Action View tests

[clayton-shopify]

Summary

Various Action View tests randomly fail with errors like the following:

ActionView::Template::Error: undefined method `__rails_actionview_test_fixtures_test__customer_erb___1906185013242363930_25680' for #<ActionView::Base:0x000000000115a8>

Here's an example of a failing build: https://buildkite.com/rails/rails/builds/84207#3bc8eb7f-c86d-4f6f-8932-e2e8c26cf893

A number of test classes use ActionView::LookupContext::DetailsKey.clear in their setup method to clear out a cache before executing tests, but the failing test classes do not have this. Adding it eliminates the failures. After making these changes, I ran the test suite in a loop (while bundle exec bin/test; do :; done) for 12 hours and did not observe any failures.

Note: I don't understand the details of the caching mechanism that's at play here, so I'm not certain that this is the best fix. I noticed some past PRs for flaky tests that could be related:

• Clear Resolvers' cache after RenderTestCases tests #36189
• Clear Resolvers' cache after AVLogSubscriberTest tests #39949
• Address ActionView::Template::Error at CI #44269