Update dashboard to clear previous plot

[radka-j]

Closes #450

I tested this in the workflow notebook and it works for me.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 81.47%. Comparing base (0abea75) to head (d282b64).

Files with missing lines	Patch %	Lines
autoemulate/history_matching_dashboard.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #510      +/-   ##
==========================================
- Coverage   81.48%   81.47%   -0.02%     
==========================================
  Files         107      107              
  Lines        7503     7504       +1     
==========================================
  Hits         6114     6114              
- Misses       1389     1390       +1     

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[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
autoemulate
history_matching_dashboard.py					404
Project Total

This report was generated by python-coverage-comment-action