Remove use of ServiceLevel in server-extra.sql
Remove use of ServiceLevel in server-extra.sql

ServiceLevel is not stored in NormalisedSuperSummaries so either the
normalised values or a proxy for ServiceLevel is used.

- Remove ServiceLevel and division by 1000 from VSumCPU and VUserCPU views
  as normalised durations are used.
- Replace ServiceLevel in VSpecIntHistory and VHepSpecHistory views with
  calculation based on NormalisedWallDuration and WallDuration as

tofu-rocketry/apel,stfc/apel,stfc/apel,apel/apel,tofu-rocketry/apel,apel/apel