Island: Remove try/except from MimikatzResultsEncryptor.encrypt()

Catching this exception was a workaround for an issue that was resolved
in PR #1508.

monkey/infection_monkey/system_info/windows_cred_collector/mimikatz_cred_collector.py

@@ -16,6 +16,8 @@ class MimikatzCredentialCollector(object):
     def cred_list_to_cred_dict(creds: List[WindowsCredentials]):
         cred_dict = {}
         for cred in creds:
+            # TODO: This should be handled by the island, not the agent. There is already similar
+            #       code in monkey_island/cc/models/report/report_dal.py.
             # Lets not use "." and "$" in keys, because it will confuse mongo.
             # Ideally we should refactor island not to use a dict and simply parse credential list.
             key = cred.username.replace(".", ",").replace("$", "")

monkey/monkey_island/cc/server_utils/encryption/dict_encryption/field_encryptors/mimikatz_results_encryptor.py

@@ -14,16 +14,9 @@ class MimikatzResultsEncryptor(IFieldEncryptor):
     def encrypt(results: dict) -> dict:
         for _, credentials in results.items():
             for secret_type in MimikatzResultsEncryptor.secret_types:
-                try:
-                    credentials[secret_type] = get_datastore_encryptor().encrypt(
-                        credentials[secret_type]
-                    )
-                except ValueError as e:
-                    logger.error(
-                        f"Failed encrypting sensitive field for "
-                        f"user {credentials['username']}! Error: {e}"
-                    )
-                    credentials[secret_type] = get_datastore_encryptor().encrypt("")
+                credentials[secret_type] = get_datastore_encryptor().encrypt(
+                    credentials[secret_type]
+                )
         return results
 
     @staticmethod