format keyword in document not overriding _metadata.yml

Bug description

the format keyword in the yaml block of a document is not overriding the format settings from the _metadata.yml in the same directory.

Steps to reproduce

I've created a repo here which demonstrates the issue https://github.com/anielsen001/quarto-yaml-test

in this project, run

quarto render test/test.qmd

and get the following output:

Executing 'test.ipynb'
  Cell 1/1: ''...Done

pandoc 
  to: html
  output-file: test.html
  standalone: true
  title-prefix: Yamltest
  section-divs: true
  html-math-method: mathjax
  wrap: none
  default-image-extension: png
  css:
    - ../styles.css
  toc: true
  
metadata
  document-css: false
  link-citations: true
  date-format: long
  lang: en
  theme: cosmo
  title: test file
  

Executing 'test.ipynb'
  Cell 1/1: ''...Done

pandoc 
  to: ipynb
  output-file: test.ipynb
  standalone: true
  default-image-extension: png
  
metadata
  ipynb-title-block: /opt/quarto/share/formats/ipynb/templates/title-block.md
  title: test file
  
Output created: ../_site/test/test.html

While I've set the format keyword in the test/test.qmd file to be only html, I still get the jupyter notebook output specified in the test/_metadata.yml file.

Expected behavior

I expect the yaml block in the file to override the directory settings in the_metadata.yml file. At least that's my interpretation of this section of the documentation: https://quarto.org/docs/projects/quarto-projects.html#metadata-merging

Actual behavior

I'm trying to suppress the jupyter notebook output on a per file basis when the _metadata.yml file specifies this behavior for the entire directory.

Your environment

text file editor

Quarto check output

quarto check
Quarto 1.4.554
[✓] Checking versions of quarto binary dependencies...
Pandoc version 3.1.11: OK
Dart Sass version 1.69.5: OK
Deno version 1.37.2: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
Version: 1.4.554
Path: /opt/quarto/bin

[✓] Checking tools....................OK
TinyTeX: (not installed)
Chromium: (not installed)

[✓] Checking LaTeX....................OK
Using: Installation From Path
Path: /usr/bin
Version: 2019

[✓] Checking basic markdown render....OK

[✓] Checking Python 3 installation....OK
Version: 3.12.1
Path: /home/apn/proj/quarto/metadata_override/yamltest/venv/bin/python3
Jupyter: 5.7.2
Kernels: python3

[✓] Checking Jupyter engine render....OK

[✓] Checking R installation...........(None)

  Unable to locate an installed version of R.
  Install R from https://cloud.r-project.org/