Revert "initialize Dialect$2 as part of strict-image-heap enforcement"

This reverts commit d3f0047.

Author: diegomarquezp

src/main/resources/META-INF/native-image/com.google.cloud/google-cloud-spanner-jdbc/native-image.properties

@@ -2,6 +2,5 @@ Args = --initialize-at-build-time==com.google.cloud.spanner.IntegrationTestEnv,\
   com.google.cloud.spanner.jdbc.it.JdbcIntegrationTestEnv,\
   com.google.common.collect.RegularImmutableMap,\
   com.google.cloud.spanner.Dialect,\
-  com.google.cloud.spanner.Dialect$2,\
   com.google.spanner.admin.database.v1.DatabaseDialect,\
   org.junit.runners.MethodSorters