dropping stash with reftable dont work

[zotttelbart]

Version

7.1.0.202411261347-r

Operating System

Windows, Linux/Unix, MacOS

Bug description

Drop a stash in a repo which is migrated to reftable ends up in

java.lang.UnsupportedOperationException: Dropping stash not supported on this ref backend

Actual behavior

Migrate a repository to reftable and use StashDropCommand.

Expected behavior

The stash should be dropped like on refdirectory refbackend.

Relevant log output

(from egit)
java.lang.UnsupportedOperationException: Dropping stash not supported on this ref backend
	at org.eclipse.jgit.api.StashDropCommand.<init>(StashDropCommand.java:62)
	at org.eclipse.jgit.api.Git.stashDrop(Git.java:683)
	at org.eclipse.egit.core.op.StashDropOperation$1.run(StashDropOperation.java:58)
	at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:2457)
	at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:2482)
	at org.eclipse.egit.core.op.StashDropOperation.execute(StashDropOperation.java:69)
	at org.eclipse.egit.ui.internal.commit.command.StashDropHandler$1.runInWorkspace(StashDropHandler.java:69)
	at org.eclipse.core.internal.resources.InternalWorkspaceJob.run(InternalWorkspaceJob.java:43)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)

Other information

Copy from eclipse-egit/egit#78. I closed the issue in egit, because its a jgit problem

[zotttelbart]

I tried to solve the issue:

Pushed https://eclipse.gerrithub.io/c/eclipse-jgit/jgit/+/1208607 and https://eclipse.gerrithub.io/c/eclipse-jgit/jgit/+/1208608

needs review