Deprecate GPUStatsMonitor and XLAStatsMonitor in favor of DeviceStatsMonitor

[daniellepintz]

What does this PR do?

Deprecates GPUStatsMonitor and XLAStatsMonitor, as they can now be replaced by the DeviceStatsMonitor which calls get_device_stats on the Accelerator interface.

Part of #9032

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[codecov]

Codecov Report

Merging #9924 (73580a3) into master (940b910) will decrease coverage by 4%.
The diff coverage is 75%.

@@           Coverage Diff           @@
##           master   #9924    +/-   ##
=======================================
- Coverage      93%     89%    -4%     
=======================================
  Files         179     179            
  Lines       15745   15780    +35     
=======================================
- Hits        14597   14010   -587     
- Misses       1148    1770   +622     

[tchaton]

LGTM ! Great work !