Fix resource-level audit w/expressions

There was an (obvious) bug leading to MID-9382.

Tested manually by running MiscSyncTest (there's no
easy way of parsing logs to automate the checks).

repo/repo-common/src/main/java/com/evolveum/midpoint/repo/common/AuditHelper.java

@@ -175,7 +175,9 @@ public AuditEventRecord evaluateRecordingExpression(ExpressionType expression, A
                         ? (AuditEventRecord) returnValue.getRealValue()
                         : null;
             } finally {
-                ExpressionEnvironmentThreadLocalHolder.popExpressionEnvironment();
+                if (expressionEnvironmentSupplier != null) {
+                    ExpressionEnvironmentThreadLocalHolder.popExpressionEnvironment();
+                }
             }
         } catch (Throwable t) {
             LoggingUtils.logUnexpectedException(LOGGER, "Couldn't evaluate audit recording expression", t);