Remove ContributionManager and ContributionPane UI files #300

Job	Run time
Test Processing	2m 32s
(windows/x64) Create Processing Build	5m 40s
(linux/x64) Create Processing Build	8m 49s
(macos/aarch64) Create Processing Build	3m 34s
(linux/aarch64) Create Processing Build	6m 57s
(macos/x64) Create Processing Build	6m 47s
	34m 19s

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