[NBS 1.0] Deprecate isomorphic git class

[camilaibs]

Hey, I just made a Pull Request!

Closes: https://github.com/backstage/backstage/issues/24604 Deprecated isomorphic Git abstraction from the backend-common package.

:heavy_check_mark: Checklist

• [x] A changeset describing the change and affected packages. (more info)
• [ ] Added or updated documentation
• [ ] Tests for new functionality and regression tests for bug fixes
• [ ] Screenshots attached (for UI changes)
• [x] All your commits have a Signed-off-by line in the message. (more info)

[backstage-goalie[bot]]

Changed Packages

Package Name	Package Path	Changeset Bump	Current Version
@backstage/backend-common	packages/backend-common	patch	v0.22.0-next.2
@backstage/plugin-scaffolder-node	plugins/scaffolder-node	patch	v0.4.4-next.2

[github-actions[bot]]

Uffizzi Cluster pr-24605 was deleted.

[github-actions[bot]]

Thank you for contributing to Backstage! The changes in this pull request will be part of the 1.27.0 release, scheduled for Tue, 14 May 2024.