[SB][Wifi] Remove activity logs from table log.

We never get any bugs related to the activity indicators being wrong,
and they really clutter up the bug report.

Bug: NONE
Flag: NONE (log changes only)
Test: dump WifiTableLog and verify there's no activity logs (even if the
config is on)

Change-Id: Ib58dfa2a07043adc1beb7d55ce2049e73c445ad2