Cherry-pick PR #39925: [ROCm] Remove deprecated hipCtx_t and HIP context APIs

[magaonka-amd]

Imported from GitHub PR openxla#39925

Summary

Remove deprecated hipCtx_t and HIP context APIs from the ROCm backend, replacing them with hipSetDevice/hipGetDevice as recommended by AMD since ROCm 1.9.

• Simplify RocmContext to a header-only class with inline methods
• Make RocmContext a value field of RocmExecutor (no heap allocation)
• Remove 7 deprecated HIP context API calls
• Remove 6 deprecated API wrappers from rocm_driver_wrapper.h
• Delete rocm_context.cc ## Motivation
  AMD has deprecated all hipCtx* and hipDevicePrimaryCtx* APIs since ROCm 1.9 with the warning "might not be supported in future releases." On ROCm, hipCtx_t is a thin wrapper around a device ordinal -- the entire context lifecycle is a no-op. A future ROCm release could remove these APIs and break the build.

Test plan

• Tested GPU device discovery (8x MI300X)
• Tested matmul, memory allocation, multi-GPU peer transfer, device synchronization, rapid context switching across 8 GPUs Copybara import of the project:

--
d32fefc by Pham Binh phambinh@amd.com:

[ROCm] Remove deprecated hipCtx_t and HIP context APIs

Replace all deprecated hipCtx_t-based context management with hipSetDevice/hipGetDevice as recommended by AMD since ROCm 1.9.

On ROCm, hipCtx_t is a thin wrapper around a device ordinal and the entire context lifecycle (Retain/Release/SetCurrent/GetCurrent) is a no-op. AMD has deprecated these APIs with the warning "might not be supported in future releases."

Changes:

• rocm_context.h: Simplify RocmContext to a trivial class holding only device_ordinal_. Remove Create(), context map, mutex, GetDeviceMemoryUsage, GetDeviceTotalMemory.
• rocm_context.cc: Deleted. Method implementations (SetActive, IsActive, Synchronize) moved into rocm_executor.cc.
• rocm_executor.h: Change RocmContext* to a value field initialized in the constructor. No heap allocation or factory needed.
• rocm_executor.cc: Update all usages from pointer to address-of. Inline DeviceMemoryUsage and GetDeviceTotalMemory. Simplify DeviceFromContext() to use context->device_ordinal().
• rocm_driver_wrapper.h: Remove 6 deprecated API wrappers (hipCtxGetDevice, hipCtxSetCurrent, hipDevicePrimaryCtxGetState, hipDevicePrimaryCtxSetFlags, hipDevicePrimaryCtxRetain, hipDevicePrimaryCtxRelease).
• BUILD: Remove rocm_context.cc from srcs, simplify deps.

Merging this change closes openxla#39925

COPYBARA_INTEGRATE_REVIEW=openxla#39925 from ROCm:phambinh/remove-deprecated-hip-ctx-apis d32fefc PiperOrigin-RevId: 895760864