This PR fixes flaky test failures in the Instagram webhook specs that
were caused by Redis mutex lock conflicts when
tests ran in parallel.
### The Problem:
The InstagramEventsJob uses a Redis mutex with a key based on sender_id
and ig_account_id to prevent race
conditions. However, all test factories were using the same hardcoded
sender_id: 'Sender-id-1', causing multiple
test instances to compete for the same mutex lock when running in
parallel.
### The Solution:
- Updated all Instagram event factories to generate unique sender IDs
using SecureRandom.hex(4)
- Modified test stubs and expectations to work with dynamic sender IDs
instead of hardcoded values
- Ensured each test instance gets its own unique mutex key, eliminating
lock contention
c31325e982