fix: rm fallback from submit v2.1 mutation

[LinHuiqing]

Problem

Fallback for virus can mutation catches all errors. This is an issue as when malicious files are scanned, the fallback is triggered as well. This bug was identified by @KenLSM in #6777.

Solution

There are many points of failure for the mutation to fail. The original intention of the fallback mechanism is to try the submission again if there are any unexpected errors related to the virus scan itself (e.g. if lambda is down, if s3 uploads can't be done, etc). However, these block submissions anyway - the response to this should be to rollback using the growthbook flag.

As such, we want to remove the onError block.

Breaking Changes

• No - this PR is backwards compatible

Bug Fixes:

• Malicious file scan triggering retry on submit fetch on storage mode form.

Tests

• Go to a storage form with attachments.
• Submit a malicious file (get a test one from https://www.eicar.org/download-anti-malware-testfile/). An error message should be thrown and submission should be blocked.

[LinHuiqing]

Decided to not remove the fallback for #6777 as soft validation is useful (though not originally intended). Will be revisited!