Server: Dropping containers results in auth data loss

[BA]

Description of bug
Whenever I send DDLs (reproduced with a pair of Create/Drop Keyspace) to a Auth-Enabled instance, the whole auth data will be gone (the file is deleted).
I can run the DDLs whatever times I like but once I ctrl+c the instance after the DDLs are executed, the next time I run the instance it gives the following message and I'll have to start all over from auth claim

ERROR skyd] Storage engine error: I/O error while reading file data/ks\system\auth: 系統找不到指定的檔案。 (os error 2) (the Chinese means `File not found`)

Steps to reproduce

1. On Windows, run skyd with Auth enabled
2. Run skysh and create a keyspace/table, then drop it
3. Ctrl+C the skyd instance then run it again.

Meta

• Release tag: 0.7.5
• Operating system: Windows 10

Additional context
This bug is reported through Discord, the source of the error is already identified by @ohsayan and a fix is scheduled to be backported to 0.7 and pushed to 0.8.

[Sayan]

Fix out in #277. Will close this once we backport the fix. Please keep this open until then. Thanks!

[Sayan]

The fix has been backported and will be released into 0.7.6. Thank you for helping in investigating this issue!