fix: Don't disable bindless allocation using an undocumented env var

[ph0b]

Bindless allocation is a core functionality. Having obscure mechanisms disabling it at runtime leads to unwanted side effects, leading to application issues, for example on applications trying to use SYCL bindless textures, that are supposed to be available unconditionally on DG2 and newer (when texturing is supported).
This is what is assumed here:
https://github.com/oneapi-src/unified-runtime/blob/dd7d5c6256f7ec90be9753e6e5a24d06a6b36fd6/source/adapters/level_zero/device.cpp#L1095

This reverts commit 81644a4.

[HoppeMateusz]

Why are bindless textures needed in SYSMAN mode?

in SYSMAN_NO_CONTEXT_MODE - Wddm context is not created so there is no GPU execution possible. Application setting this mode is not executing any kernels on GPU

[ph0b]

As this environment variable is not publicly documented, I didn't have all the context and couldn't make assumptions beyond the name that to me, indicated an init mode specifically for sysman usage, configured through an environment variable that is potentially not directly controlled by applications.

I agree bindless doesn't make sense when no context is created yet, the concern was rather about the use of the environment variable itself, and that there could be cases in which this environment variable would remain set while the application is going to use more than sysman and execute GPU kernels later.
From other uses of this env var such as

compute-runtime/shared/source/os_interface/windows/os_context_win.cpp

Line 36 in 8ec5434

bool disableContextCreationFlag = envReader.getSetting("NEO_L0_SYSMAN_NO_CONTEXT_MODE", false);

and what you've said, it seems it cannot be the case, and if it was the case, the impact would go beyond just bindless allocations.