Now that Bluetooth proxy is enabled, change default setting to passive

[morris2009]

Hi, i noticed that apparently some time ago the bluetooth proxy feature is enabled in the v3 powerplug YAML.
I noticed because my MiFlora flower sensor now ran thru their batteries quite quickly because the default setting for the bluetooth sensor is set to active scanning.

My suggestion would be to change the setting to Passive scanning, instead of active scanning to not do too much harm in existing environments.

esp32_ble_tracker:
  scan_parameters:
    active: false