Revert "[BACKEND] Enhance the 2D Block io lowering for tt.store. (#4561)" (#4635)

Revert due to #4625 and #4633.

Flex Decoding UTs CI:
https://github.com/intel/intel-xpu-backend-for-triton/actions/runs/16130696752
(passes)
Benchmark CI:
https://github.com/intel/intel-xpu-backend-for-triton/actions/runs/16130667335
(passes)

This reverts commit 244c285 and
9752a56.

Author: whitneywhtsang

include/triton/Tools/Sys/GetEnv.hpp

@@ -51,7 +51,6 @@ inline const std::set<std::string> CACHE_INVALIDATING_ENV_VARS = {
     "TRITON_INTEL_ENABLE_INSTR_SCHED",
     "TRITON_INTEL_FAST_MATH",
     "TRITON_INTEL_REDUCE_TRANSPOSE",
-    "TRITON_INTEL_ENABLE_BLOCK_IO_STORE_ON_REGULAR_PTR",
     // clang-format on
 };