This is disabled by default and enabled with this change.
This has the following effect:
- Deactivate automatic garbage collection using gc_disable() before the
first test is run
- Trigger garbage collection using gc_collect_cycles() before the first
test is run
- Trigger garbage collection using gc_collect_cycles() after each n-th
test
- Trigger garbage collection after using gc_collect_cycles() after the
last test was run
- Activate automatic garbage collection using gc_enable() after the last
test was run
Resolves: #1328
