feat(sfs): Refactor wait handler to use new WaiterHelper

[j1n-o9r]

…e wait helper

Description

Update the wait handler of sfs, to use the new WaiterHelper struct. Replace every possible wait handler implementation of this service, to use just the WaiterHelper.

relates to STACKITSDK-368

Checklist

• Issue was linked above
• No generated code was adjusted manually (check comments in file header)
• Changelogs
  • Changelog in the root directory was adjusted (see here)
  • Changelog(s) of the service(s) were adjusted (see e.g. here)
• VERSION file(s) of the service(s) were adjusted
• Code format was applied: make fmt
• Examples were added / adjusted (see examples/ directory)
• Unit tests got implemented or updated
• Unit tests are passing: make test (will be checked by CI)
• No linter issues: make lint (will be checked by CI)