Does not fully close #24361 (this is only a first, simple change set)

Summary:

• where the type of the operands allows, change expectEqual(x, y) to expect(x == y) for files in test/behavior/**

# without these changes (master branch)
$ git grep expectEqual test/behavior | wc -l
1028

# with these changes
$ git grep expectEqual test/behavior | wc -l
348

My editor was configured to re-order imports on save. Hope that isn't a huge issue.

Verification evidence:

• the CI should pass, no new tests are introduced, only changes to existing tests