Increase coverage and consistency of trip planner tests #5694

Job	Run time
Build application and assets	6m 16s
file_changes	6s
Build Docker image	7m 5s
Formatting / Elixir	3m 10s
Formatting / JavaScript & TypeScript	30s
Linting / Elixir	3m 34s
Linting / TypeScript	36s
Unit tests / JavaScript / Mocha	46s
Unit tests / JavaScript & TypeScript / Jest	2m 9s
Linting / JavaScript	21s
Linting / CSS	26s
Type checks / Elixir	4m 0s
Type checks / TypeScript	39s
Unit tests / Elixir / mix coveralls.html	1m 10s
	30m 48s

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