wifi: remove legacy field merging codes

If an SAE config is merged into a PSK+SAE config, this part
would overwrite legacy fields by SAE legacy fields which lead to
inconsist default security type, i.e. legacy fields are SAE type,
but default security params type is PSK (the first one of the security
params list).

Obsolete tests are removed because legacy fields are not allowed be
modfied directly.

Bug: 181951838
Bug: 182059157
Test: atest FrameworksWifiTests
Change-Id: I623c98fc39391fce2e943f2b100a8cf529701b08
3 files changed