Fix SpaSearchLandingActivity.isValidCall()

SettingsIntelligence sometimes starts SearchResultTrampoline first,
in this case, SearchResultTrampoline checks if the call is valid, then
SearchResultTrampoline will start this SpaSearchLandingActivity, allow
this use case.

Fix: 370186204
Flag: EXEMPT bug fix
Test: manual - search roaming
Change-Id: Ib6b2c1d3b8754f478a637dda8e9df77a91b24d9e