Changed cow health and milking updates to America/Los_Angeles time

[Edwin-Yee]

Overview

Tested changes locally by setting the update time to 2:51pm PST and I observed that the milking was done exactly at 2:51pm PST.

Screenshot of my test is here.

The test was deleted and the original code is unchanged in my PR.

Tests

• [x] npm test
• [x] npm run coverage
• [x] npx stryker run

Closes #7