Changes

stp: Define IUT default T(beat) in mp_t_beat_sec_default

Several tests expect to know this value from the IUT in order to test
related features. Since it will be used in more places in follow-up
patches, move it so the information only needs to be configured once.

Change-Id: Ic518e0d35f377fef85344177b630eb8599ec22d0

stp: Validate timer xua beat 0 disables BEAT procedure

Check in all sort of configurations that the BEAT procedure on xUA/IPA
can be disabled just fine per ASP using the VTY.

Related: SYS#8156
Change-Id: Id47bf862638a099bb5f6721fcfba873001aed616

eim/testenv: put mnesia database into volatile location

When running the TTCN3 testsuite in testenv, we create the database
files in a non-volatile location. This means that with every
consecutive test run, the database from the first test run is
re-used. This may lead to unexpected behaviour.

With this patch we change the location of the database to a volatile
location, so that each testrun uses a fresh database.

Related: SYS#8100
Change-Id: I178e4fcd29880668467b6deaa44f44d142b8c29c