fix non-pipelinelayer to distributed

[gongel]

PR types

Bug fixes

PR changes

APIs

Description

• When model is not pipelinelayer, it will assert error.

[paddle-bot]

Thanks for your contribution!

[ZHUI]

PPO情况下，主模型是 pp, dummpy的模型非 pp 导致的问题

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 52.80%. Comparing base (7551730) to head (4abc545).
Report is 258 commits behind head on develop.

Files with missing lines	Patch %	Lines
paddlenlp/trainer/trainer.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #9310      +/-   ##
===========================================
- Coverage    52.80%   52.80%   -0.01%     
===========================================
  Files          660      660              
  Lines       106869   106870       +1     
===========================================
- Hits         56434    56432       -2     
- Misses       50435    50438       +3     

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