refactor: add new test-suite 'tests-timer-stress'

Moved 'Stress test timer framework' as part of 'tests-extensive' suite
by creating a separate test suite for timers, i.e. tests-timer-stress.

Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
Change-Id: Ibdad88e81fba55333c0ad17cc9c10d24d97e6c7e
(cherry picked from commit 309d95eb37808ee136e42015f81690cd5c8972bf)
6 files changed