sap_hana_preconfigure: Allow setting THP to any possible value

[berndfinger]

This provides more flexibility for example when testing different THP settings.

For this purpose, we are introducing a new role variable, named sap_hana_preconfigure_thp. Possible values are those displayed when running the command cat /sys/kernel/mm/transparent_hugepage/enabled:

• always
• madvise
• never

See also #879 .