Update benchmarking for diffusers

[ajrasane]

What does this PR do?

Type of change:
Example update

Overview:

• Optimize the benchmarking function in the diffusers example

python diffusion_trt.py --model flux-dev --benchmark --model-dtype BFloat16 --skip-image --torch

Testing

Backbone-only inference latency (BFloat16):
  Average: 139.48 ms
  P50: 139.36 ms
  P95: 141.13 ms
  P99: 141.35 ms

Before your PR is "Ready for review"

• Make sure you read and follow Contributor guidelines and your commits are signed.
• Is this change backward compatible?: Yes
• Did you write any new necessary tests?: No
• Did you add or update any necessary documentation?: No
• Did you update Changelog?: No

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.39%. Comparing base (4b522e0) to head (89f6c25).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #487   +/-   ##
=======================================
  Coverage   73.39%   73.39%           
=======================================
  Files         180      180           
  Lines       18134    18134           
=======================================
  Hits        13310    13310           
  Misses       4824     4824           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[kevalmorabia97]

Please make sure to run internal gitlab diffuesrs cicd test to verify they dont break with this change