the external storage backend becomes dirty after parse any external storage URL

[Leavrth]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

./br restore point -s "s3://temp/log?sse-kms-key-id=123" --full-backup-storage "s3://temp/full"

2. What did you expect to see? (Required)

1. The external storage has sse-kms-key-id=123 in the log restore.
2. The external storage has not sse-kms-key-id=123 in the snapshot restore.

3. What did you see instead (Required)

1. The external storage has sse-kms-key-id=123 in the log restore.
2. The external storage also has sse-kms-key-id=123 in the snapshot restore.

4. What is your TiDB version? (Required)

master