policy fuzzer: ignore known panics

[AdamKorcz]

Summary

Ignore panics like these:

1. https://github.com/cue-lang/cue/blob/c905888d93236a7398dd5ff07d436bb41762f2ed/cue/literal/string.go#L216
2. https://github.com/cue-lang/cue/blob/c905888d93236a7398dd5ff07d436bb41762f2ed/internal/core/adt/eval.go#L1326

Which OSS-Fuzz has reported here:

1. https://issues.oss-fuzz.com/issues/382721853
2. https://issues.oss-fuzz.com/issues/371237561

Release Note

Documentation

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 36.48%. Comparing base (2ef6022) to head (f296a19).
Report is 266 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3993      +/-   ##
==========================================
- Coverage   40.10%   36.48%   -3.63%     
==========================================
  Files         155      209      +54     
  Lines       10044    13316    +3272     
==========================================
+ Hits         4028     4858     +830     
- Misses       5530     7839    +2309     
- Partials      486      619     +133     

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