Default implementation of setup_execution_config uses "device" mcm

[astralcai]

Context:

Description of the Change:
Update the default implementation of Device.setup_execution_config to use the "device" MCM method if "device" is available, regardless of finite shots or not.

Benefits:
Aligns with the default strategy discussed.

Possible Drawbacks:
The only devices affected by this are one that defines a TOML file with "device" included in its mcm methods, and does not override preprocess, which is none of the devices.

Related GitHub Issues:
[sc-95418]

[github-actions]

Hello. You may have forgotten to update the changelog!
Please edit doc/releases/changelog-dev.md with:

• A one-to-two sentence description of the change. You may include a small working example for new features.
• A link back to this PR.
• Your name (or GitHub username) in the contributors section.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.68%. Comparing base (cc5600c) to head (d9ea6c8).
⚠️ Report is 424 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #7968   +/-   ##
=======================================
  Coverage   99.68%   99.68%           
=======================================
  Files         542      542           
  Lines       55650    55650           
=======================================
  Hits        55476    55476           
  Misses        174      174           

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[andrijapau]

Nice