`AdvancedTable`: use correct icons in th-button-expand #14447

Job	Run time
Get files changed and conditionally skip CI	12s
Tests	5m 59s
ember-lts-3.28	5m 27s
ember-lts-4.12	3m 3s
ember-beta	3m 1s
embroider-safe	3m 4s
embroider-optimized	1m 6s
	21m 52s

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