[vcpkg baseline][realsense2] Fix config issue on osx

[PhoebeHui]

Related to #18106

Fix the following issue on osx platform:
From https://github.com/IntelRealSense/librealsense/blob/master/CMakeLists.txt#L14, there is no internet connection, so BUILD_WITH_TM2 was disabled. IMPORT_DEPTH_CAM_FW as well.
However, https://github.com/IntelRealSense/librealsense/blob/master/CMake/unix_config.cmake#L38 directly set the BUILD_WITH_TM2 to ON, it overrides the previous checks, and it ignore the IMPORT_DEPTH_CAM_FW check, that cause the error.

Remove it from CMake/unix_config.cmake since it should be in control of the previous checks in CMakeLists.txt.

CMake Warning at CMakeLists.txt:22 (message):
  No internet connection, disabling IMPORT_DEPTH_CAM_FW

CMake Error at src/tm2/CMakeLists.txt:16 (message):
  BUILD_WITH_TM2 requires IMPORT_DEPTH_CAM_FW
Call Stack (most recent call first):
  src/CMakeLists.txt:57 (include)
  CMakeLists.txt:56 (include)

Report an issue IntelRealSense/librealsense#9124 to Upstream

[JackBoosY]

Ping @strega-nil-ms for merge this PR first.