Temporarily rescue Module::DelegationError in worker

What does this MR do?

Groups::ExportMembershipsWorker is currently raising Module::DelegationError in circumstances where User records are unavailable. That is causing these workers to fail and be re-tried, only to fail again. That is particularly a problem due to the ongoing rapid action for Redis saturation. To avoid this impact on infrastructure while we troubleshoot the bug, this adds a temporary rescue clause to the worker. This clause will be removed when the bug is fixed in a follow-up MR.

See #338707 (closed)

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Related to #338707 (closed)