Adjust hessian_reg to fix Arnoldi test case (#1388)

Summary:
Pull Request resolved: #1388

Increase hessian regularization term for Arnoldi test to ensure that highest self-influence datapoint / proponent match the corresponding example

Reviewed By: craymichael

Differential Revision: D64584502

fbshipit-source-id: da36364888ea9423cdbbacb949e78d077982de09

Author: Vivek Miglani

tests/influence/_core/test_tracin_regression.py

@@ -376,6 +376,7 @@ def _test_tracin_identity_regression_setup(
                 DataInfluenceConstructor(
                     ArnoldiInfluenceFunction,
                     arnoldi_tol=1e-8,  # needs to be small to avoid empty arnoldi basis
+                    hessian_reg=2e-3,
                 ),
             ),
         ],