Removing lm_eval as a third-party module (#3793)

Summary:
The third-party module was added when the install requirements wasn't working for lm_eval.

Since the latter was fixed, the module is unused. Harmless removal

Pull Request resolved: #3793

Reviewed By: lucylq

Differential Revision: D58037012

Pulled By: Jack-Khuu

fbshipit-source-id: c57b4781d08fa3b4c3a0a3f2eb6de1a6ee3b591d

Author: Jack-Khuu

.gitmodules

@@ -49,10 +49,6 @@
 [submodule "backends/vulkan/third-party/Vulkan-Headers"]
 	path = backends/vulkan/third-party/Vulkan-Headers
 	url = https://github.com/KhronosGroup/Vulkan-Headers
-[submodule "third-party/lm-evaluation-harness"]
-	path = third-party/lm-evaluation-harness
-	url = https://github.com/EleutherAI/lm-evaluation-harness
-	branch = v0.4.1
 [submodule "kernels/optimized/third-party/eigen"]
 	path = kernels/optimized/third-party/eigen
 	url = https://gitlab.com/libeigen/eigen.git