Use faker.helpers where appropriate

[iamacook]

Summary

There are faker.helpers that we are not leveraging in our tests, instead using proprietary workarounds. This changes the following throughout the project:

Object keys

// from
faker.helpers.arrayElement(Object.keys(...))
// to
faker.helpers.objectKey(...)

Enum values

// from
faker.helpers.arrayElement(Object.values(...))
// to
faker.helpers.enumValue(...)

Array samples

// from
Array.from(
  { length: faker.number.int({ min: n, max: m }) },
  () => builder(),
);
// to
faker.helpers.multiple(
  () => builder(),
  { count: { min: n, max: m } },
);