SupplicantScanner: Truncate hidden network list

Truncate the hidden network id list if it goes beyond wpa_supplicant's
max value. wpa_supplicant has a hard coded value of 16 for the max
number of networks that can be specified for each scan.

There is currently no way to query this value from wpa_supplicant, so
hardcoding this value in SupplicantScanner.

BUG: 28632556
Change-Id: I31a338b91c221c1686437b738894e13abb897474
TEST: Compiles & unit-test passes
2 files changed
tree: 4cb33fc65f952d5a5c99bde2e1d24297c662803e
  1. service/
  2. tests/