Revert "Support multi users scenarios in Tapl"

Revert "Reduce multi users tests runtime"

Revert "Add PlatformTesting to dependency."

Revert "Move platform testing util to separate gradle module"

Revert submission 20311444-user-switch-nosleep

Reason for revert: Part of DM+Platinum montiro as a likely culprit for b/257210412. Won't be submitted if proven otherwise.
Reverted Changes:
I90b1069de:Support multi users scenarios in Tapl
I706da86a3:Add PlatformTesting to dependency.
I605cd76c4:Move platform testing util to separate gradle modu...
I64b571dc4:Reduce multi users tests runtime

Change-Id: I6310efa59fe1755feb29bef28d890e684b7164c6