reset_identity edge case when the user has several backup version server side

[BillCarsonFr]

As per code the reset flow should:

matrix-rust-sdk/crates/matrix-sdk/src/encryption/recovery/mod.rs

Lines 348 to 354 in 7ec384c

	/// Completely reset the current user's crypto identity.
	/// This method will go through the following steps:
	///
	/// 1. Disable backing up room keys and delete the active backup
	/// 2. Disable recovery and delete secret storage
	/// 3. Go through the cross-signing key reset flow
	/// 4. Finally, re-enable key backups (only if they were already enabled)

The problem is that if there are several version published on the server, this code will only delete the "current" one.

Then step 4. will fail with BackupExistsOnServer

On the js-sdk there is some code to delete all backup versions

[BillCarsonFr]

step to reproduce:

• use a client that allows to add a new backup without deleting the previous one.
• Try to reset identity from EX => reset will fail

[poljar]

This is somewhat related to: #4190.