Wifi: Mark tests with @Test

To appease Errorprone, mark methods that look like tests with @Test.

Also, fix a bug discovered by one of these tests.

(cherry picked from commit 44cf2158a84459cf2275ab4c42637e6bc801c4bf)

Bug: 72076216
Test: m javac-check RUN_ERROR_PRONE=true
Test: ./frameworks/opt/net/wifi/tests/wifitests/runtests.sh
Merged-In: I400f6371c7d964e2eb8943976d0365938b75d64c
Change-Id: I400f6371c7d964e2eb8943976d0365938b75d64c
2 files changed