Don't require other gate approval prior to API owners

[RByers]

Describe the bug
From discussion with API owners and dharani@ a few months back, I believe we aligned on expecting people to pursue API owners and other review gate approval in parallel. API owners are supposed to ask for the other reviews to be started, and engineers are supposed to wait for all gates to be approved before shipping, but API owners don't block on seeing approval of other gates before giving their LGTM. I believe this was a change made during the new process design in order to reduce the risk of additional latency from pipeline stalls.

To Reproduce
Steps to reproduce the behavior:

1. Request review for security, debuggability and privacy for OT
2. Click "draft I2E" button
3. See warning about being "strongly encouraged" to wait for approval on security / privacy / debuggability (sorry I forgot to take a screenshot when I saw it)

Expected behavior
Warn if the reviews have not been requested, but not if they're still just pending.

Additional context
I didn't test the I2S case myself, but perhaps it's similar?