BTS_Tests: explicitly configure Intave in TC_pcu_interf_ind

Starting from [1] osmo-bts does average the interference levels as
defined by the Intave parameter before reporting over the PCUIF.

In TC_pcu_interf_ind we expect to receive an interference report
every 480ms (one SACCH period), so let's the Intave to 1.

[1] osmo-bts.git I3fbaad5dbc3bbd305b3ad4cb4bfb431a42cfbffc

Change-Id: I070b195af8c62454edd8de961cce6be2c120ae48
Related: SYS#5313
1 file changed