Support rhel8 in attach script

[crhuff-ibm]

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Relates #3987

Output from acceptance testing:

$ make testacc TEST=./ibm/service/satellite TESTARGS='-run=TestAccIBMSatelliteAttachHostScriptDataSourceBasic'
=== RUN   TestAccIBMSatelliteAttachHostScriptDataSourceBasic
--- PASS: TestAccIBMSatelliteAttachHostScriptDataSourceBasic (1259.67s)
=== RUN   TestAccIBMSatelliteAttachHostScriptDataSourceBasicCoreos
--- PASS: TestAccIBMSatelliteAttachHostScriptDataSourceBasicCoreos (1179.38s)
PASS
ok      github.com/IBM-Cloud/terraform-provider-ibm/ibm/service/satellite       2439.918s

[crhuff-ibm]

This PR is based on what the bootstrap team does to spin up and test rhel 8 clusters, and makes what we put on our host script in line with that. It also removes unnecessary/overly broad package allowances.