MGMT-14904: fix error code for ignition size validation

On update InfraEnv, should return StatusBadRequest(400),
when discovery ignition image size validation fails.

internal/bminventory/inventory.go

@@ -5013,7 +5013,7 @@ func (b *bareMetalInventory) UpdateInfraEnvInternal(ctx context.Context, params
 
 	// Validate discovery ignition after updating InfraEnv data
 	if err = b.validateDiscoveryIgnitionImageSize(ctx, infraEnv, params, tx, log); err != nil {
-		return nil, err
+		return nil, common.NewApiError(http.StatusBadRequest, err)
 	}
 
 	tx.Commit()

internal/bminventory/inventory_test.go

@@ -12480,9 +12480,7 @@ var _ = Describe("UpdateInfraEnv - Ignition", func() {
 			InfraEnvUpdateParams: &models.InfraEnvUpdateParams{IgnitionConfigOverride: override},
 		}
 		response := bm.UpdateInfraEnv(ctx, params)
-		Expect(response).To(BeAssignableToTypeOf(common.NewApiError(http.StatusBadRequest, errors.Errorf(""))))
-		err = response.(*common.ApiErrorResponse)
-		Expect(err.Error()).To(ContainSubstring("over the maximum allowable size"))
+		verifyApiErrorString(response, http.StatusBadRequest, "over the maximum allowable size")
 	})
 })