Dropper QoL: droppers can now only transfer 1u 2u, or 5u #6264

Job	Run time
Run Linters	2m 36s
Collect data for other tasks	17s
Lint with OpenDream	30s
Compile Maps	2m 16s
Windows Build	1m 47s
Integration Tests (boxstation) / run_integration_tests	12m 23s
Integration Tests (deltastation) / run_integration_tests	12m 1s
Integration Tests (icebox) / run_integration_tests	54m 51s
Integration Tests (kilostation) / run_integration_tests	11m 20s
Integration Tests (metastation) / run_integration_tests	12m 16s
Integration Tests (multiz_debug) / run_integration_tests	11m 17s
Integration Tests (northstar) / run_integration_tests	11m 26s
Integration Tests (runtimestation) / run_integration_tests	9m 5s
Integration Tests (tramstation) / run_integration_tests	17m 9s
Alternate Tests (515, 1627, runtimestation) / run_integration_tests	9m 25s
Check Alternate Tests	3s
Compare Screenshot Tests	1m 11s
	2h 49m 53s

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