Fix some tests by using `runSessionWithServerInTmpDir` instead of `runSessionWithConfig`

@fendor noticed that https://github.com/haskell/haskell-language-server/pull/5020 fails because fourmolu tries to read the `haskell-language-server.cabal` during the test. It shouldn't, that's probably some implicit `fourmolu`/`ormolu` behaviour looking for a `.cabal` file.

If we run the tests in temporary directories, then we might be able to merge that PR after all. (Not really, because of Debian, see https://github.com/haskell/haskell-language-server/pull/5020#issuecomment-5426849998.)

Instead of `runSessionWithConfig`, we should be using our test runners that copy the directory into a temporary directory, e.g. `goldenWithHaskellDocInTmpDir` or `goldenWithHaskellDocFormatterInTmpDir`

Probably rather `runSessionWithServerInTmpDir` since the tests modify the configuration during the tests.