test: Remove MagicVariableTest#testServernameFromDifferentProtocols

test: Remove MagicVariableTest#testServernameFromDifferentProtocols

This test was causing failures locally when wgServer != localhost
because {{SERVERNAME}} is derived from wgServerName, not wgServer
and the test is only mocking wgServer.

> MagicVariableTest::testServername.. with data set #2 ('//localhost/')
> Magic servername should be <localhost:string>
> Failed asserting that two strings are identical.
> --- Expected
> +++ Actual
> @@ @@
> -localhost
> +krinkle.dev

This value is no longer derived by the Parser, but is instead
set using wfParserUrl in Setup.php.

Remove this obsolete test and add any missing test cases for
wgParserUrl to its test suite.

Change-Id: I7d7d201cb46841e63dac8ab9fd81b45b252264a3