tests: avoid sql queries in TitleTest

tests: avoid sql queries in TitleTest

testIsAlwaysKnown was invoked on an interwiki link. To have the test
pass, we used addDBData() to inject the interwiki in the database.  This
end up being execute on each test when it is only needed for a single
assertion.

Instead of creating a Title, use Title::makeTitle() to populate the
interwiki, thus letting us avoid the database hits.

Random timing: 1.20s -> 150ms.

Change-Id: I63a4e7b9af5eacb7dc1de4b33b8e631e6c3f1fa6