[stellar/stellar-core] Remove empty test (#1762)

Looks like a remnant of the past
You can view, comment on, or merge this pull request online at:

https://github.com/stellar/stellar-core/pull/1762

— Commit Summary —

* Remove empty test

— File Changes —

M src/herder/HerderTests.cpp (11)

— Patch Links —

https://github.com/stellar/stellar-core/pull/1762.patch
https://github.com/stellar/stellar-core/pull/1762.diff