Remove RegionBuilder and remaining references to region references #2443

Job	Run time
linux-python3.13-ros3	1m 15s
linux-gallery-python3.9-minimum	51s
linux-gallery-python3.13-upgraded	1m 15s
windows-gallery-python3.13-upgraded	2m 20s
windows-gallery-python3.9-minimum	1m 29s
linux-python3.13	2m 14s
linux-python3.13-upgraded	2m 19s
linux-python3.9-minimum	2m 2s
macos-python3.13-upgraded	1m 26s
macos-python3.9-minimum	3m 29s
windows-python3.13-upgraded	4m 27s
windows-python3.9-minimum	3m 1s
conda-linux-python3.13-upgraded	2m 12s
conda-linux-python3.9-minimum	2m 30s
Deploy pre-release from dev	0s
	30m 50s

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