Default gcAllowVeryLargeObjects to true (dotnet/coreclr#8853)

Default gcAllowVeryLargeObjects to true (dotnet/coreclr#8853)

* Default gcAllowVeryLargeObjects to true

* Update tests for gcAllowVeryLargeObjects

These 2 tests appear to rely on gcAllowVeryLargeObjects being false in that they expect an exception to be thrown when allocating a very large array.

Increase the number of array elements so that an OutOfMemoryException is always thown no matter what value gcAllowVeryLargeObjects has. 81*98*58*36*74*4 is 4906065024 which is larger than 2^32, the theoretical array length limit.

Commit migrated from https://github.com/dotnet/coreclr/commit/163983ecf59c70d7c286e740f7cd3230f12a0f3c