fix(DiffFlameGraph): Remove non-working pprof export

[grafakus]

✨ Description

Related issue(s): -

This PR fixes the error that occurs when trying to export a diff flame graph to pprof:

📖 Summary of the changes

The export relies on using the legacy query parameter to fetch the profile in pprof format. But:

• it's incorrect because the diff profile depends on both baseline & comparison queries
• the query parameter has been deprecated when migrating the plugin to Scenes

🧪 How to test?

The "pprof" export in the export menu should not be present anymore

[github-actions[bot]]

Unit test coverage

Lines	Statements	Branches	Functions
	10.68% (478/4473)	8.21% (136/1656)	7.99% (109/1364)