Fix shared weights sync for PipelineLayer

[DrownFish19]

PR types

Bug fixes

PR changes

Others

Description

1. PipelineLayer will create parameters for each layer and call _synchronize_shared_weights() to synchronize the shared parameters.
2. When setting the model state_dict, _synchronize_shared_weights will be called to synchronize the shared parameters. However, self._init_weights will re-initialize the parameters without synchronizing the shared parameters. If the following step does not load a checkpoint, the shared parameters will be different.

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[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (0658258) 57.30% compared to head (9c2ce79) 57.30%.

Files	Patch %	Lines
paddlenlp/transformers/model_utils.py	66.66%	1 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           release/2.7    #7775      +/-   ##
===============================================
- Coverage        57.30%   57.30%   -0.01%     
===============================================
  Files              584      584              
  Lines            87688    87690       +2     
===============================================
+ Hits             50252    50253       +1     
- Misses           37436    37437       +1     

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