dev guide: add jvm-option required for HarvestingServerIT.testMultiRecordOaiSet to succeed

[donsizemore]

In perhaps a "required jvm-options" subheading beneath Integration Tests at https://guides.dataverse.org/en/latest/developers/testing.html

asadmin create-jvm-options "-Ddataverse.oai.server.maxidentifiers=2"
asadmin create-jvm-options "-Ddataverse.oai.server.maxrecords=2"

Pull request forthcoming.

[pdurbin]

@donsizemore thanks! Very likely your PR should mark this issue as closes as well:

• Update "Getting Set Up to Run REST Assured Tests" #9738